Directed by: Brian De Palma
Starring: Tom Cruise, Jon Voight, Ving Rhames, Jean Reno, Kristin Scott Thomas, Vanessa Redgrave, Henry Czerny, Emmanuelle Béart
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)
Factual error: The vents that Hunt and his sidekick crawl down at CIA Headquarters are standard galvanized steel box vents; they are very common in the building trade. Try walking or crawling down one - you'll make a noise like the sky is falling down. People will be able to hear you for miles. Every person in that building would know somebody was crawling about in the vent system. (This error applies to dozens of films, not only this one.)
Suggested correction: "People will be able to hear you for miles. Every person in that building would know somebody crawling about in the vent system." No, they won't. The sound from someone crawling through a vent would carry for metres but not miles. CIA Headquarters are quite large, so it's unlikely that the sound would carry to every part of it. And even if it did, there's no reason to believe that every person in the building would know that the sound was somebody crawling about in the vent system.
The galvanised steel the box vents are made out of makes a very distinctive booming sound when it distorts under pressure, and it is loud. Unless they are deaf, the people in the room through which the vent runs would know perfectly well that there was someone in there.
Question: Was Kreiger going to kill Ethan Hunt above the vault immediately after grabbing the disk from Ethan's mouth? Earlier when Ethan says, "Zero body count," Kreiger responds "We'll see," insinuating maybe he's still planning to kill somebody. As soon as Ethan's to the top, Kreiger grabs the disk, a quick, "Merci" (as if saying thanks, now goodbye), and the knife is already out, but luckily dropped. They are both so freaked out at such a near miss, Ethan doesn't even notice Kreiger was going to kill him. Did this cross anybody else's mind? Why else was the knife out to be dropped?
Answer: I disagree with the other answers. I watched it in slow motion and thought he was going for the kill. There would be minimal struggle since Ethan isn't in a fighting position and Krieger was inches from his throat with the knife before he dropped it. He wouldn't care if there's a lock down because he would be out by the time they notice Ethan's body above. I guess blood spilling would give it away, but he'd still be out and under cover before anything can be done. He doesn't have to know who Max is or how to contact her he's working with Claire and Phelps. Luther wouldn't care too much because he just met them. At most all they have to say is that there was an accident and Ethan didn't make it. Max wouldn't care because she just wants the real list. If Ethan dies early the bad guys win and IMF will think hey he was the mole and got double crossed. There is 0 reason for Krieger to not kill him at that moment. He has the disc and that's all he needs.
Job as Jim lost confidence of Max. The deal was with Ethan. Ethan had to survive.
Answer: Krieger presumably used his knife to kill the rat in the vent. It's unlikely he would have tried to kill Ethan above the vault, as there would have been a noisy struggle which would set off the intrusion countermeasures. Luther would have also seen it happen on Ethan's head-mounted camera.
Also, Krieger didn't know how to communicate with Max.
Krieger didn't need to communicate with Max because he was actually working with Claire and Jim, and Jim was in communication with Max.
Krieger may have killed the rat with the knife, but that's not why it's in his hand when he confronts Ethan. After killing the rat, he has both hands on the cable holding Ethan.
Answer: He killed the rat with the knife and didn't have time to pull it out then. You can see the rat lying there with the knife still in. Only when Ethan is up again, Krieger retrieves the knife, a perfectly innocent move. Whether he intended to use the opportunity to kill Ethan, we don't know.
Answer: I don't think he intended to kill him. If so, why would Ethan continue to work with a guy who literally just tried to murder him? But I also have no idea why Krieger had the knife out.