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)
Revealing mistake: When John attacks the 3 bad guys in the residence area, one of them throws John into the wall which wobbles. (01:00:35)
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)
Revealing mistake: When we see Cadillac One cutting over some grass, marks from previous takes are visible. (01:12:50)
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