Corrected entry: When Mario and Luigi are wrestling two dinosaurs. Luigi gets flung in the air and Mario gets swung around and thrown in the air, when the two bump into each other, Mario and Luigi swap colours so Mario is green and Luigi is red. When the scene cuts to the next thing they're back to normal.
Super Mario World (1991)
1 corrected entry
Starring: Tabitha St. Germain, Walker Boone, Catherine Gallant, Judy Marshak
Genres: Animated
Audio problem: When the wizard says "Bob-ombs", he says it twice so where he says it before the bomb appears and after. But the second time he says it, his mouth doesn't move at all. It just stays open as a smile.
Correction: This swap was caused by the two brothers bashing into each other. As for how they suddenly changed back to normal this was most likely done for comic effect.