When Rita kicks the Frenchmen through the wall of the café, the hole appears before he makes it. It later enlarges itself when Rita is kicked through.
The first time Fozzie answers the phone, he walks off with the earpiece, indicating it's not actually attached to the phone.
It is obvious when the Frenchmen is replaced by a dummy, as he has less body mass than when he is played by a person in a costume.
In the talk spot, Jim Henson's arm is visible performing Kermit when Rita shouts at him for reading the cue cards.