The play "The Nightman Cometh" became a real-life limited-engagement play, based entirely on this episode.
The set built for the play is a replication of Charlie and Frank's apartment.
The tune Charlie whistles when he leaves The Waitress is the same tune used at the point where it cut to commercials throughout the series.
The German Shepard Hitler painting is re-created on the wall of the musical set .
The way Charlie pops out at The Waitress is the same exact way Dee did in Episode 7 of this season, :"Who Pooped The Bed?".