For your next enjoyable trip down Continuity Lane, Matt is referring to when he and Simon were going through Stephanie's home back in Chapter Two. Specifically, the lobby room with the door illusion and the "Dead Matts" room.

This trip down Continuity Lane has been brought to you by the fact that I had to dig back through all my comics to recreate those two rooms for this comic, painfully diving back through how my art has improved over the past few years in the process, so now you have to as well.