Revealing mistake: When Ethan uses the magnetic screwdriver to undo the screws holding the grille to the air-vent in the NOC list room, the spindle that is actually turning the screw is visible after it falls out.
Revealing mistake: When we see a close-up of a knife being pulled out of a man's stomach, it's obviously a prop knife where the blade goes into the handle, as we can see the end of the blade while it's being pulled out. (01:19:50)
Answer: Jim has not been paid (at least in full) yet. This is revealed in the conversation Ethan has with Max in the car. Payment was conditional on the disk passing all her safety checks, which she had not done yet (she had not even looked at it yet). There is no way Jim knew the NOC list was junk at this point in time. However, since Jim has not been paid yet for the NOC list, he might have been trying to play it safe, and have Claire just keep tabs. If things don't go as planned, he might have left Claire as she was expendable to him. Also it is unlikely Max contacted Jim (Job) to ask about the email from Ethan (pretending to be Job). Max at this point believes the two are the same person. She simply invites Job to come in and discuss further.