Continuity mistake: When Cale asks his ex-wife what he has done, he has the envelope he is holding in one hand in one shot and both hands in the next. (00:10:05)
Continuity mistake: When John and Emily are in the car at the start, the way John holds the envelope changes between shots. Note the flap. (00:11:20)
Continuity mistake: In Cale's interview, just before agent Todd starts making a noise, Maggie is holding a fact sheet about Cale. The way she holds it changes between shots. (00:16:40)
Continuity mistake: When John and Emily start their tour, the guide asks them where they're from. After that, they start to walk towards one hallway. John and Emily are in the back. The next shot, they're in the front of the pack. There would not have been enough time for this to happen. (00:28:00 - 00:29:00)
Continuity mistake: Towards the end of the movie when John is talking to the President after he got shot in the watch, John has a wound on his right arm. A few minutes later when John is outside the White House you can see his wound is different, it's bigger and there's lots more blood. (01:52:50 - 01:55:30)
Chosen answer: Grenades generally do not make any sound until they detonate. When you release the spoon (lever) as you throw it, it can make a "ping" sound as its separates from the grenade. No clockwork noises. (I'm ex Army).
stiiggy