Revealing mistake: Towards the end of the episode, as Frasier is on the lounger by the windows, a power cord is on the ground going through the far left window (where glass should be), possibly going to the lamp.
Revealing mistake: I think there might be something wrong with the eels in this episode. They don't move in the tank, despite being alive and don't move when taken out either. Moreover, you cannot actually see any in the tank with one exception. Rubber replacements not up to standard obviously.
Chosen answer: The turkey's stuffing.