Continuity mistake: In this episode Alan says that he gave Judith diamond earrings while out, and that she filed for divorce then kicked him out and he moved in with Charlie. However, at the start, Alan is kicked out, and it's several months later that Judith files for divorce as he receives the papers and it's a plot point in that episode (S1 E8).
Factual error: Alan and Lyndsey are playing scrabble. Alan is shown laying tiles down horizontally, and claims that he is using the "Z" on a triple letter score, and the "I" on a double word score, changing "it" to "ziti". This is impossible on a normal Scrabble board - those multiplier squares are all offset from each other except one row, and then they're five squares apart.