Carla tries to get Eddie's old jersey number (38) retired by the Boston Bruins. In season 5, Cliff mentions Eddie's number is 33.
Just before the beer absorption test, Rebecca is holding a beer with half a head, the next shot just an inch or so.
Lilith mentions that Frederick is "about a week old." According to tradition...a bris is normally performed when the child is 8 days old.
Woody claimed to have had smallpox as a child. The last case of smallpox in the US was in 1949, long before Woody was born.
When Fraiser and Lilith bring Frederick into the bar, just after Fraiser tells Cliff to stay away from the baby; while Sam is asking if they have picked out a name yet, you can see Bebe Neuwirth crack up and start laughing.
After Woody says, "Those pants I can hide". Rebecca is running into the bar from the pool room. You can briefly see what looks like part of a camera in the upper right hand corner of the scene.
Lilith uses the noun form - "meshuggener" (crazy person) - when she should have used the adjective form - "meshuga" (crazy).