The Hammer - S6-E2
Revealing mistake: When Bradford is fighting The Hammer, you can plainly see it's a stunt double for Tim whenever he is thrown over a table or into the wall.
Training Day - S6-E4
Continuity mistake: When Tim and Aaron are questioning a suspect, Aaron comes out of the room to talk to Tim and shuts the door behind him. When it cuts back to Aaron, the door is open. (00:09:16)
Answer: Window tool.