Visible crew/equipment: Just as the Rangers find a way to defeat Lord Zed's putties, we see a camera shot circulating the rangers. Pay attention and you will see that there is one shadow on the ground that doesn't move. Clearly from a member of the film crew. (00:16:40)
Revealing mistake: When Rita is shrunk and put into her travelling vessel, the shrunken Rita is a very bad model. (00:12:20)
Answer: Probably to save on costs of filming the same scene. In the reused shots they have always morphed so you can't see the actors. They just have to pay them to do voice-overs rather than the entire scene.
Ssiscool ★