Other mistake: When assembling the Zeo Megazord, Zeo Zord V is the last to join, forming the head and back of the Zeo Megazord. When it has connected, we see all 5 Rangers slide down simultaneously into the head of the Zeo Megazord. Where it is piloted from and where did they slide down? The head has only just joined, and the other 4 Zeo Zord forms the rest of the body - not enough time for them ALL to slide up, and then back down again.
Other mistake: In the closed-captioning, when Arnold and Gerald "touch thumbs" (and you hear that "sproing" sound), the caption says "[glass shatters]"
Monkey Fun - S2-E13
Other mistake: Season 2 episode 13 "Monkey Fun": Just before the enlarged Titano appears at the zoo, there is a family watching normal-sized monkeys in a cage. The family father (farthest on the right) has a drawing disorder with his eyes: their pupils look up and down, respectively, giving him a rather goofy expression.
Other mistake: When Bruce Banner is attempting to rescue the nun from the fire, a beam falls from the ceiling and hits him in the head, triggering his transformation into the Hulk. Just before he starts his transformation, a set of green glowing eyes appear above his head. It appears the animators didn't properly sync the glowing eyes onto Banner's face.