Other mistake: As Denny asks "did she sleep in your room?" Alan leaves Denny's hotel room, pulling the door behind him. The swinging door catch is in the closed position, sticking out from the door frame which would prevent the door from being able to shut - the shot cuts a fraction before impact and we hear the sound of the door closing anyway.
Boston Legal (2004)
1 other mistake in season 3 - chronological order
Starring: James Spader, William Shatner, Candice Bergen, Rene Auberjonois
Revealing mistake: When Denise is showing Brad how to kiss, the first kiss is a typical "stage kiss" with their lips pretty clamped shut, but she then details what he's doing wrong with his tongue, which clearly wasn't at all involved with the sort of kiss they just shared.
Brad Chase: I outrank you.
Alan Shore: And I'm such a slut for authority.
Trivia: Alan mentions networks even censoring their scripted shows - that's a pointed reference to the fact that ABC executives ordered any explicit references of Fox News to be removed from this episode.