3 Ninjas

Deliberate mistake: During the sting attempt towards the beginning, Douglas confronts Snyder on the roof of the building. A helicopter rises up from nowhere without making any sound prior to that.

Other mistake: 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?

More mistakes in 3 Ninjas

Fester: Hey dude, what time does school get out?
Hammer: I don't know. I never stayed to the end.

More quotes from 3 Ninjas