The first cartoon selected for the National Film Registry.

In animation historian Jerry Beck's 1994 poll of animators, film historians and directors, this cartoon was selected as the #1 cartoon of all time.

Warner Bros. Cartoons, Inc. only allotted five weeks for the production of each seven-minute short, but director Chuck Jones spent seven weeks on this short. To cover up for the extra time spent, he had his entire unit doctor their time cards to make it appear as if they working on the Road Runner/Coyote short Zoom and Bored (1957) for two weeks before they actually started (since Chuck and his staff were so familiar with the Road Runner formula, they were able to complete Zoom and Bored in three weeks).

According to Chuck Jones, there are 104 cuts in this cartoon, an unusually high number for a Warner Bros. cartoon.

For the ballet scenes, Chuck Jones and his animators studied dancers Tania Riabouchinskaya and David Lichine, who were working for Warner Bros. at the time. Both dancers had previously worked on Fantasia (1940), as reference models for the "Dance of the Hours" sequence.

When Elmer is summoning the various forces of nature ("North Wind bwow! South Wind bwow!" etc.), Mel Blanc does the summoning on the final incantation ("Smog!") because Arthur Q. Bryan's reading was not strong enough. Bryan's reading of the line can be heard on the Looney Tunes Golden Collection Volume 2 DVD vocal only audio track.

When presented in the 1979 compilation The Bugs Bunny-Road Runner Movie, Bugs Bunny claims that the short was the whole of Wagner's 17-hour Opera Cycle "Der Ring des Nibelungen" (The Ring of the Nibelung, which he mispronounced as "The Rings of Nibble-lung" in his Brooklynese accent), condensed into only 7 minutes. He also pronounced Richard Wagner the way it looks (wag-ner), instead of Rikard Vagner. Besides the second opera of Ring, Die Walküre (The Valkyrie) and the third opera of the Ring, Siegfried, other Wagnerian music present in the cartoon comes from Tannhäuser and Der fliegende Holländer (The Flying Dutchman).

Specific excerpts include:
the overture from The Flying Dutchman — opening storm scene
Siegfried's horn call from Siegfried — "O mighty warrior of great fighting stock"
the overture and "Pilgrims’ Chorus" from Tannhäuser — "O Bwünnhilde, you'w so wuvwy," "Return my love," and the closing scene
the Bacchanal from Tannhäuser — ballet scene between Elmer and Bugs

What's Opera, Doc? required about 6 times as much work and expense as any of the other 6-minute cartoons his production unit was turning out at the time. Jones has admitted as much, having described a surreptitious re-allocation of production time to completing the short.

During the 6 minutes of What's Opera, Doc?, Jones lampoons:
Disney's Fantasia,
the contemporary style of ballet,
Wagner's perceived ponderous operatic style, and even
the by-then clichéd Bugs-and-Elmer formula.

Michael Maltese devised the story for the cartoon, and also wrote lyrics to Wagner's music to create the duet "Return My Love". Art director Maurice Noble devised the stylized backdrops for the cartoon. The cartoon drew upon some previous Warner studio work; the concept of Bugs in Valkyrie drag riding a fat horse to the Tannhäuser Pilgrim's Chorus was originated by Friz Freleng in the suppressed 1945 wartime cartoon Herr Meets Hare.

Released in 1953, but completed and copyrighted in 1951. During this late forties-early fifties period, Warner Bros., MGM and Disney/RKO stockpiled many cartoons, releasing them a year or two after completion.

According to Chuck Jones, the revelation of the animator in the ending is just for comedic value - Jones (the director) is speaking to the audience directly, asking "Who is Daffy Duck anyway? Would you recognize him if I did THIS to him?"

In animation historian Jerry Beck's 1994 poll of animators, film historians and directors, this cartoon was rated the second greatest cartoon of all time.

This cartoon nearly didn't get made because there was resistance to the idea of using Bugs Bunny in such a limited role near the end.

SPOILER: Bugs Bunny needed to be used at the end, because no other character had any kind of antagonism with Daffy (acquired by Bugs over the course of the Hunting Trilogy in Rabbit Fire (1951), Rabbit Seasoning (1952) and Duck! Rabbit, Duck! (1953)) and Elmer Fudd is not a competent enough character - an ironic point considering the next year Elmer Fudd gets his animator's shots at Bugs Bunny in Rabbit Rampage (1955).

The film is celebrated for its surreal humor, such as when Porky is chasing the bird, it disappears and suddenly the Warner Brothers shield emerges from the horizon's vanishing point, as it typically did at every cartoon's beginning, and complete with the standard stretched "boing" of the steel guitar. The Do-Do comes from behind the shield to bop Porky on the head and we see the shield immediately turn to return to the horizon with the bird riding it there (with, consequently, the boing sound played in reverse). The Do-Do character is much like the very early Daffy Duck in voice and mannerisms.

Among the crazy characters Porky encounters is a creature with three heads arguing amongst themselves in gibberish talk. From the haircuts on the three heads, it is clear that this is a parody of The Three Stooges. The character then faces the camera and leans into it in such a way that their round heads form a triangle, and a small character explains to the audience that, "He says his mama was scared by a pawnbroker's sign!"

At one point in the pan of the various denizens of Wackyland, a character with large glasses comes out of a pot and says, "Hello, Bobo." This refers to animator Robert Cannon, whose nickname was Bobo and who did wear big glasses. On the pot are the words "Treg's a Foo", refering to sound effects man Treg Brown. (Foo, incidentally, is a nonsense word from the Smokey Stover comic strip, a big influence on this cartoon in terms of humor and visual style.)

Much of the Wackyland sequence was adapted and reused by Clampett for inclusion in his 1943 short Tin Pan Alley Cats. A color remake of Porky in Wackyland was supervised by Friz Freleng in 1948. Re-titled as Dough for the Do-Do, the remake was released in 1949. The films were nearly identical, in many cases appearing to match frame-by-frame in certain details, albeit with Porky's appearance updated and the voices having evolved, and many of the backgrounds being different.

First (and, as far as many people are concerned, only) appearance of Michigan J. Frog.

The main character's name, "Michigan J. Frog", was created long after the cartoon was produced. Michigan J. Frog later became the mascot of the Warner Brothers television network ("The WB").

Steven Spielberg once described this as "the most perfect cartoon ever made".

The retrospectively-given name of Michigan J. Frog is derived from the one song he sings in this cartoon that Chuck Jones and Michael Maltese wrote especially for him, "The Michigan Rag". Jones came up with the middle initial after being interviewed by a writer named Jay Cox.

The song "Michigan Rag" was invented solely for this short.

No voice is heard except the frog in the short.

Some believe that the story of this frog was at least partly inspired by a real amphibian. In Eastland, Texas they tell the story of one horned toad named Old Rip. He was placed in the cornerstone of the courthouse there in 1897. In 1928 the courthouse was demolished and the story is that they pulled Old Rip out and he was still alive (he did not get up and dance however). Eleven months later, Old Rip finally "croaked" and the citizens made him a fancy velvet-lined casket and put him on permanent display, where you can still see him today. In 1973, an anonymous person claimed that he wanted to come clean about Old Rip. He claimed that it was all a hoax back then and they had switched the dead "original" toad with a live one. No-one has ever come forward to verify this claim, but most think it is probably true that it was a prank. Whatever the real story, the legend of Old Rip has some interesting similarities to the frog in "One Froggy Evening".

The singing voice of the frog is provided by Bill Roberts, a popular Hollywood nightclub singer of the 1950s. Many sources erroneously credit Terence Monk with supplying the singing voice of the frog. This error appears to be rooted in an interview in which Chuck Jones identified him as such. However, he was not the baritone heard in the film. The confusion may have been caused by the fact that Jones did use Monck in "The Cat Above and the Mouse Below", where he sang "Largo al factotum" (from Rossini's "Il barbiere di Siviglia"/"The Barber of Seville").

Due to the cartoon, "Dancing Frog" is now computer terminology for a computer problem that will not appear when anyone else is watching.

Several of the songs performed by the frog were written after he was presumably sealed into the cornerstone, dated 1892. They include:

"Hello! Ma Baby"
Words and Music by Ida Emerson and Joseph E. Howard (1899)

"The Michigan Rag"
Words and Music by Milt Franklyn, Michael Maltese and Chuck Jones (original song written for the cartoon)

"Come Back to Erin"
Words and Music by Claribel (pseudonym of Charlotte Alington Barnard) (1866)

"I'm Just Wild About Harry"
Words and Music by Eubie Blake and Noble Sissle (1921)

"Throw Him Down, McCloskey"
Words and Music by John W. Kelly (1890)

"The Michigan Rag" reprise

"Won't You Come Over To My House"
Words by Harry Williams
Music by Egbert Van Alstyne (1906)

"Largo al factotum"
from "The Barber of Seville"
Composed by Gioacchino Rossini (1816)

"Please Don't Talk About Me When I'm Gone"
Words and Music by Sidney Clare, Sam H. Stept and Bee Palmer (1930)

"Hello! Ma Baby" reprise