Movie Nut

Revealing mistake: As the camera pans down to Kermit sitting in the empty sound stage, it's easy to tell that the sides of the stool are actually solid with the background painted on them to hide the puppeteer.

Movie Nut

Revealing mistake: When Fozzie comes out on stage and starts his act, you can see lines around him, suggesting he was matted into the scene. He also reacts a second too late to the gun being shot by him, and he doesn't cast a shadow.

Movie Nut