Development Gag: The gaming studio that developed the Wii version is located in Salmon Arm, British Columbia in Canada. Which is where they decided to have Bear Hugger—and even named one of his moves—from.note He'a actually from Saskatoon, Saskatchewan, at least according to the Super NES game.
Bear Hugger is voiced by Richard Newman (who coincidentally lives in Bear Hugger's home province of British Columbia), who is well known for playing Rhinox, another big guy. Not only that, he voiced a certain M.Bison who said "yes".
Piston Honda is voiced by Kenji Takahashi, who also voiced Abel from Street Fighter IV.
Spanish players may also recognize the voice of Don Flamenco being Juan Amador Pulido, a Spanish voice actor for such roles as Tom Tucker and Cleveland of Family Guy, Shadow the Hedgehog from Sonic X, Gabriel of Dexter and The Captain of WALL•E.
Charles Martinet provided pretty much all the voices in the SNES Super Punch-Out. He is more recognizable as the voice of Mario and Luigi (among others).
In the NES version, a camera held by an audience member at the top-right corner of the screen will flash when Bald Bull's bull charge can be countered.
Little Mac (or someone that looked like him) was going to be the player character in the SNES Super Punch-Out!! before being replaced by the blond boxer for unknown reasons. Nintendo has flip-flopped over whether this character is Mac with a makeover or an entirely new boxer for several years.
Meme Acknowledgment: In the Wii game, Doc Louis may joke about stealing Mac's bike in the chatter between rounds.
No Export for You: Inverted. Japan didn't get a release of Super Punch Out for SNES, except for a very limited edition in March 1998.
Talking to Himself: Great Tiger in Title Defense mode makes several illusions of himself between rounds. They hang out on the ropes talking like they're on break.
In a more straight example, Doc Louis and Mr. Sandman are both voiced by Riley Inge.
These two characters are also the only ones that refer to Little Mac as "Mac baby".
In an interesting coincidence, the initial barrage of punches Mike Tyson hammers you for in the NES version lasts 91 seconds, the amount of time it took Tyson to knock out contender Michael Spinks in 1988.
The only boxers to appear in all three console versions of the game are Bald Bull, Super Macho Man, and Mr. Sandman. Due to Arcade Super Punch-Out being a Mission Pack Sequel, no boxer has appeared in all games.
Unintentional Period Piece: The NES game, with Mac's pink track suit, Popinski being from the USSR, Great Tiger's hometown being named "Bombay", and Mike Tyson being champ definitely set it in the '80s. If Mac's able to beat Super Macho Man, we see a paper that gives the date as April 1, 1987.