Continuity mistake: It is visible that Dr Gordon's handwriting when he writes " I know who you are", is different from the handwriting in Hoffman's letter.
Continuity mistake: Saw VII takes place straight after Saw VI. In Saw VI we see Jill put Hoffman in the bear trap and leave. We then see that Hoffman spends around 45 seconds trying to get the trap off before putting in the bars on the window. In this film however, just after Jill closes the door we see the glass break. No delay.
Plot hole: Gideon speaks to Jill about her fingerprints being all over the bear trap. When he does he says that there is a new game going on, referring to Bobby's game. However, the police are unaware of this game at this point. He can't be referring to the garage trap as he says that the game is going on, and the garage trap has already happened.
Continuity mistake: When we see the bear trap at the start of the film, there is a small amount of blood on the trap from when Hoffman was in it. Later, when it's left on show for Gideon, there is a lot more blood on the trap. The device is nowhere near any other victims for their blood to spill on to it.