(At 15:48-16:11) When Steed lines up to shoot the can, there is no speaker in front of the cans. After Steed shoots one can Steed passes the gun to Dr. Vilner who turns on a speaker that just appears as he shoots the next 3 cans.
(at around 50 mins) As Steed takes aim at the can with the gun, a TV camera can be seen to the far right above the last can.