When Will and Caleb are in the ritual room they have a conversation just before Will falls. There are three times that we hear this conversation. The first time we hear it is when it actually happened, the second is when Caleb has a flashback of it, and the last time is the surveillance video that Lucas and his friends watch. The conversations change each time. For example when Will says that he doesn't have Caleb's book with him, he says that they can "get it anytime" and he also says that "we can get it later".