When the Order take Martin Ruber into the locked room of objects, the camera pans across the objects the order has collected, amongst them is a black 1960s style dial type telephone. Although this is in period, there is a wall mounted phone in the room, it is unlikely there would have been two telephones in the room and even less likely the occupant would have brought one with him.
At about 21 mins, on the bank website, the word "withdrawal" is misspelled.
When Joe sleeps in the Room he makes a dream where the phone is ringing. His gun is on the bedside table pointing away from the wall; when he wakes the gun points to the wall.
Jennifer says that the Comb makes Harold almost unbeatable. Despite that, Joe defeats Harold and gets the Comb pretty easily. Granted, he has the Key, but two people operating in tandem could have done the same thing Joe did by teleporting ahead of Harold to flank him.
Stritzke is showing Joe how the comb works. Stritzke tells Joe to freeze time, and take the book from his hands. Joe freezes time, and tries to take the book but he can't. Stritzke explains to Joe that when time is frozen, everything is frozen, you can't use any objects, not even open a door. However earlier when Stritzke was in the store picking up his film, he stole money from a cash register when he froze time.