In Cry Harder, Sam celebrates getting the bar back by erasing Norm's tab.
Frasier and Lilith got married in February 1988. Here it is February 1992, yet they are celebrating their 5th wedding anniversary, not their 4th!
Sam says that Norm's bar tab goes back to when he first started coming to Cheers - but it has been paid off or cancelled in previous episodes, so presumbaly Norm would have started a new tab!
Finally, where were Niles and Martin this time? They didn't go to Frasier's real wedding, or Frederick's circumsion, and now they are a no show at this...
Frasier: Paul, is this a toaster oven?
(Frasier is fretting about his mother-in-law coming to visit)
Frasier: I suppose it's wrong of me to blame Betty for all our problems. I'm sure I'm not the way she wants me to be either.
Woody: How does she want you to be, Dr. Crane?
Frasier: Well... dead. The thing that really drives me crazy is the unrelenting tension between Lilith and her mother. You know, Lilith just holds it all in. She has to unload it somewhere and guess who gets to listen to it endlessly.
Woody: Apparently me, Dr. Crane.
(Lilith is frustrated because her mother is controlling her)
Cliff: Still can't get your mother off your back, huh? It's very difficult for me to relate to.
Lilith: (sarcastically) Really?
Cliff: Oh, yeah. Ma and I don't have any problems. You know, in fact, most people find it's hard to tell that we're even related. Folks down at Club Med are very surprised when they find out we're mother and son... shocked even.