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.
The Return of the Beast: Part 2 - S1-E2
Other mistake: After the Abomination abducts Bruce Banner from the cavern, he causes a complete cave-in at the entrance. When Rick and Betty come to, they are able to see perfectly fine despite the sun being completely blocked out. Rick even states when he and Betty start to remove all the rocks that are blocking the opening that they need to find some blue sky before they can find Bruce.