Revealing mistake: When Walters is electrocuted, the kettle on his head is not resting on it but is fixed on the grid behind him, as to prevent it from falling off. Since Walters moves his head slightly, so should the kettle.
Continuity mistake: In the beginning when Topper is about to fight, he puts a red bandana around his head. As he is walking to the fight, one of the flaps of the bandana is draped over his shoulder. The shot changes when he gets to the fight, and both flaps are now behind his shoulders.
Continuity mistake: When Topper is trying to get the keys to free the colonel, he knocks the pepper-shaker over, but there's no visible concentration of pepper. After the colonel gets the keys, a mouse is shown on the table. It goes up to the newspaper and sneezes from the mound of pepper which was not there before.
Revealing mistake: When Topper is fighting the Thai Fighter, they break the ladder that sends some people falling down. Before the shot cuts, you can see the guy with the pink shirt falling, and he has a dummy attached to him. This is not the same as other dummies who are obviously meant to be noticed (like the guy holding the "John 3:17" sign).
Visible crew/equipment: When Michelle is at the dinner she asks Topper for a light and strikes it on her leg. As she starts to move her leg, you can see the black strip on her leg to light the match.
Continuity mistake: When Harbinger jumps out the plane he has face paint on but when he lands it's gone.
Revealing mistake: When Walters strikes down his guard with the fly-swatter, he slumps against the wall, but actually never comes in contact with the 'Halarm' switch.
Revealing mistake: The cloud which drenches Topper at the railroad station casts no shadow over him.