Revealing mistake: When morphing, a "Net" appears over the Rangers, which their Zeo powers then morph them over. Tommy and Tanya's nets don't match their bodies - for example, their shoulders aren't in the net, yet they disappear when their Ranger costume appears.
Monkeyman! / Buses, Bikes and Subways - S5-E1
Revealing mistake: Mr. Simmons counts 30 students in the bus, but nowhere near that many got off (nor have nearly that many fourth graders ever been shown).