Chess Pains - S3-E18
Other mistake: When Frasier sets off the fire alarm Daphne comes running from her bedroom at the end of the hall across from Martin's room and Frasier's room. That is incorrect and impossible since Daphne's Room is on the other end of the condo and separated by the balcony. Given the condo layout, it is impossible for Daphne's bedroom to have a door across from Frasier's bedroom.
Chosen answer: The turkey's stuffing.