Continuity mistake: Morgan gets a call from BAU and we see him holding his phone in one hand then two. (00:03:40)
Continuity mistake: When Gideon is talking when we first see him, the pictures behind him on the screen change instantly. It should be noted, that when we see the pictures change, there is the audible click and visual delay of a slide change which is not present on the instant change. (00:04:20)
Continuity mistake: At the start we see Spencer explaining to Gideon about the Boston Strangler, his orange shirt is untucked at the front with both sides of his shirt being visible. Camera shows Gideon walking off and now only 1 side of his shirt is untucked. (00:05:10)
Character mistake: Morgan asks Reid what track on the CD (Some Kind of Monster by Metallica) would help an insomniac sleep. Reid replies with "Enter Sandman" however, Some Kind of Monster doesn't feature the song Enter Sandman. (00:29:00)
Suggested correction: Morgan doesn't ask what song on that album would speak to an insomniac, he asks what Metallica song in general would. He says, and I quote, "Okay, so I'm an insomniac who listens to Metallica to get to sleep. What song could possibly speak to me?" His query is in regards to the band's discography as a whole; neither he nor Reid mention a specific album, so the fact that "Some Kind of Monster" is the CD that they find is, ultimately, irrelevant.
The team was looking for what CD Slessman listened to the most to figure out what his password could be. They had no luck going through all his metal collection. The clue was suppose to be Slessman listened to "Some Kind of Monster" CD the most to help him sleep, which is why it wasn't in the case.