If he has damaged his vocal chords, he wouldn't be able to scream in pain at the sight of his son's Christmas presents on returning home, or grunt while working out. These noises pass over the vocal chords just as speaking does.
The hand grenade used for the can booby-trap detonated instantaneously when tripped. This was a U.S military M67 grenade which has a time delay fuse of 4-7 seconds after the spoon is released.
The maps used to plan the attack on the gang depict Washington, DC. The White House, Ellipse, National Mall, and Capitol Building are all visible.