Continuity: During the part when Rocky, Colt, and Tum Tum are in their room, Tum Tum is playing Nintendo. You can see he is playing Super Mario Land 3, he beats a level and then starts singing Rocky loves Emily. When Colt says "mom's coming" Tum Tum turns off the game but its at the main menu when you first start the game. You can't go to the main menu without resetting or turning the Nintendo off and on.
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Mistakes
When Colt and Rocky take on the two bullies in a basketball game, Rocky takes a backwards shot from the right side of the basket (obviously shooting towards the left). Then the basketball goes into the basket from the left side. See more...
3 Ninjas mistakes
Continuity: When Colt and Rocky take on the two bullies in a basketball game, Rocky takes a backwards shot from the right side of the basket (obviously shooting towards the left). Then the basketball goes into the basket from the left side.
Other: When the three ninjas are kidnapped and locked in that room, Tum-Tum is complaining about being hungry. Later on, before the fighting match between Grandpa and Snider, Tum-Tum gives Grandpa jelly beans. Why didn't Tum-Tum just eat those before?