Continuity mistake: When the Mystery Men smash their "Magnetic" Herkimer bus through Casanova's Castle's main gate you can see a number of the lights mounted to the front of the bus are smashed, however, in the next couple of front on shots, you can see that all lights are working and intact.
Continuity mistake: When the squad is making new costumes with the Sphinx and the Shoveller is talking to someone, the tape measure keeps changing places. First it's outside his collar, then it's inside it.
Continuity mistake: During his interview, the waffle iron held in the Waffler's right hand switched positions. At first it was being held by one side of the iron, then he was holding it by the handle, then it went back to being held by one side of the iron. His other hand had an oven mitt on it so there wasn't any way that he could have just simply switched hands.
Other mistake: During the final battle in which the Shoveler is fighting the Disco Boys, when Tony C first appears, if you look in the bottom-left corner of the screen you can see a Disco Boy in a green hat sitting unconscious against the wall. However, Shoveler never fought this man.
Continuity mistake: When the weapons builder is talking about the machine, from behind he puts one arm behind his back, but from the front both arms are out in front, gesturing. He puts one behind his back just as the shot changes.
Continuity mistake: After the Blue Raja kills Captain Amazing, they retreat to the amusement park and the lab of Dr. Heller where the Shoveler is making egg salad. He opens a large jar of mayonnaise, scoops some out, and leaves the jar on the counter. A later shot shows the counter without the mayonnaise jar. Then the jar reappears.
Continuity mistake: During Casanova's parole hearing, there is a clock on the wall behind the parole board. After Lance Hunt is done reading the "statement from Captain Amazing", this clock keeps showing different times for six shots. Whenever the camera is on the chairman of the parole committee, the clock shows 9.05 exactly, whenever it's on Hunt, the clock jumps back a few minutes, and shows 9.03.
Continuity mistake: When the Mystery Men barge into Casanova's mansion with their tank, they activate the super magnet and attract all the guns and weapons of the various gangs in the room, and later we see the Japanese gang use their guns while they (the guns) are still stuck to the magnet. This brings up one question, how could the Blue Raja and the Shoveller get out of the tank while the magnet was on without their weapons (forks and shovels) being attracted to it? [The Blue Raja throws silver, which isn't magnetic, but the shovel certainly would be...]
Continuity mistake: When the Blue Raja and his mother are having their touching moment in the attic she says that she always knew he was special, "I just didn't know how special". When she says this his is twirling 1 fork in his hand. The camera cuts as she finishes saying this and he suddenly has 3 forks in his hands. There was no time for him to get the other forks and he was not reaching anywhere near the silverware case.
Continuity mistake: After the scene in the movie where Spleen gets shot in the derriere, that he still walks like normal despite having a painful bullet wound that should inhibit the way he walks a little bit.
Continuity mistake: During the interviews for superheroes, the 2 Wonder Woman look-a-likes begin to fight. The camera then focuses on Mr. Furious and his friends. Notice the placement of food on the table in front of them. The camera cuts back to the fighting women then back to the table. The food has moved. The potato salad moved towards Mr. Furious and the hamburger disappeared.
Continuity mistake: It's possible to see the Waffleman still in line after the Mystery Men reject him at their recruiting party.
Continuity mistake: When the gang is confronting Cassanova Frankenstein in his Corvette limo, the begin to beat up the car. The same shot of the Shoveler pounding in the side of the car is used twice. The first time dents the side panel. The second time he hits the car there is no dent prior to him hitting the car and the same dent appears after he hits the car.
Factual error: Tony the disco bandit is dancing just after Casanova is released. He looks at the record player and sleeve. The record is a relatively modern vinyl stereo LP at a speed of 33 RPM. But the record player is a really antique machine for bakelite mono records that play at 78 RPM. Even if it could play the record, the sound would have been completely wrong.