Plot hole: At closing time, Cliff, Norm and Woody spontaneously decide to go to Cliff's house. Sam then enters the bar after his date at Melville's. Later in the scene, Rebecca asks Sam about the 'Three Stooges', to which Sam sarcastically replies that they went to Cliff's house. But how could he possibly know that since he entered the scene after they had already left.
Revealing mistake: When Frasier comes into the chalet after skiing he doesn't show any of the visible effects after a hard day on the slopes. Meaning, his face isn't even flushed from the cold, his hair is perfectly combed after wearing a hat and there is not even a drop of snow on his boots.
Other mistake: Right after Sam tells Carla he will sleep with the next woman who walks through the door, in the background there is an "Extra" (blonde-haired woman seen in background between Sam and Carla) who starts to cross right then turns and crosses lefts then turns right and stops and looks confused as to where she is to cross. Obviously she was given directions of which way to cross and when, but forgot.
Continuity mistake: Carla tosses Rebecca an egg she is supposed to take care of, like a baby, for a $5 wager. The egg bounces off Rebecca's hands and over the bar onto the floor. In the next scene, Lilith and Frasier are walking into the bar and the egg was shown as being smashed on the bar itself. The next cutaway, with Lilith walking by the same spot, has no egg on the bar anymore.
Audio problem: While Sam and Dianne are at Melville's after both of their lies have been revealed, when Dianne tells Sam that she came back on a quest for the truth, we hear Sam respond, "And you just brought along your one-man Warren Commission there," but his mouth is saying something entirely different.
Continuity mistake: After Don leaves the bar, a few minutes later Frasier shouts at him, "Run, Don! Run like the wind!" and Rebecca is left sitting alone at the table crying, but when it cuts to the overhead shot of the bar we see Don is still sitting at the table, even though he left five minutes earlier.
Visible crew/equipment: When Rebecca leaves Don at the table to relax while she gets champagne to "celebrate the answer", it cuts to an overhead shot as we hear the TV host introduce Salman Rushdie and Dr. Ruth, and the set lighting can be seen as well as the boom and mic moving around at the top of the screen. A few minutes later the mic can be seen bobbing again in the overhead shot from the same angle.
Continuity mistake: When Sam tells everyone it's closing time, he asks Harry how he got into the bar whilst he is playing snooker. He replies and then places a white snooker ball two inches behind a blue ball. There is also a yellow ball about three inches to the right of the blue ball. In the next shot, the yellow ball has suddenly moved a foot away from the blue ball. The yellow ball returns to its original position three inches away from the blue ball in the next shot.