Continuity mistake: Frasier is recounting what happened in Cafe Nervosa and we see the flashback - he is explaining why Bulldog is not a hero. In the flashback, we see Bulldog grab hold of Roz and he throws his coffee supposedly towards the gunman. However, the shot shows the cup rolling back towards where Bulldog was standing. In the next shot, we see the coffee cup again, hurtling towards the gunman, and spilling coffee on him.
Audio problem: This does not sound like a case of Frasier stuttering but it sounds like two sets of the same line over top of each other. When Niles sees Donny come into the restaurant, Abby and Frasier just turn to look and Niles exclaims "I said, don't look." - and Frasier says "you - you did not - not". It's as though they forgot to edit out some sound from two different shots.
Continuity mistake: When the KCAL team goes for their final weigh-in, Roz grabs some scissors and one of her co-workers cuts her hair - but he cuts it quite low towards the bottom of her ponytail - when she holds up the cut portion, she only has a few inches left to her ponytail.
Continuity mistake: When we first see Marty on the floor oiling his chair, his cane is lying on the floor with the handle end pointing towards the kitchen. When he picks it up a few shots later, it has turned 180 degrees and the handle is pointing towards the door. At no time did he touch it.
Continuity mistake: After Rick has left Roz's apartment, she goes into the kitchen with the roses and just as she gets there Frasier knocks on the door. Within a couple of seconds she comes back with the roses in a vase, but she just didn't have enough time to do this in "real time".
Continuity mistake: Abbie puts Niles' burning menu in the ice bucket where it remains for the rest of the scene, next to the bottle of champagne. Sometimes the menu is right up against the bottle and sometimes it is an inch or two apart - with no one touching either item.