When Charlie and Alan are in the bar, the position of the broken giraffe varies between shots.
When Alan and Charlie are at the kitchen table and Alan is drinking tequila, he pours two shots and drinks. The glass is shown empty. In the next shot, he picks up the glass and drinks again without refilling the glass.
During season 2, Jake, Alan and Charlie refer to Judith's new boyfriend, Dr. Melnick (Ryan Stiles), as "Greg". In s2e4 ("Go Get Mommy's Bra"), it is revealed that Judith and "Greg" have broken up. In future seasons, Judith again dates (and marries) Dr. Melnick, but his first name has changed to "Herb".