Audio problem: The post-production beep sound-fx coming out of Matrix's stopwatch is sometimes on and others off. (00:22:05 - 00:44:05)
Audio problem: During the phone-booth scene at the mall, the same woman's cry is heard over and over and over again. (00:36:00)
Audio problem: When Matrix drops Sully of the cliff, he never seems to hit the bottom or the ocean. Even with a small man like Sully you would clearly hear a splash or a thud. (00:41:20)
Audio problem: When Matrix tells Cooke that "I eat Green Berets for breakfast" you never see his lips move when he says "right now I'm very hungry." (00:46:47)
Audio problem: When the soldiers surround the shack and finish firing at it,you can hear a shotgun blast last while nobody shot. (01:11:25)
Audio problem: Towards the end there's a firefight between Matrix who wields a shotgun and El Presidente who is armed with a Steyr AUG. The weapon sounds used for the Steyr AUG however are from a MAC 10 or an UZI and don't sound a bit like it. (01:18:13)
Audio problem: The scene where Bennet and Matrix are fighting towards the end of the movie, before Matrix kills Bennet they have each others throat in their hands and one of their backs is against the furnace. While they are grunting and groaning, if you listen carefully, you can hear one of them say "switch" just before they change positions. (01:19:05)
Audio problem: When Cooke enters the motel room, the sound of the first hit that Matrix gives him happens a split second before the fist makes contact.
Audio problem: When Cooke starts up the Cadillac in the dealership you hear the engine turn over and fire twice.
Audio problem: When Arnie sets his stop watch to count down from 11hrs, each second that the watch ticks over there is a loud 'beep'. This is consistent with when he looks at his watch later in the mall, when it reads 9hrs 40mins to go, his watch is still beeping every second. Therefore, Arnie's watch should have been beeping every second of the movie in between these two scenes, but we never hear it. Also, when Arnie and Cindy arrive at the Sunspot Motel (7hrs 57min to go) and when Arnie's in the back of the police wagon, at 5hrs 2min to go, the watch no longer beeps with each passing second.
Answer: Possibly so any surviving enemies they encountered on previous missions and or tours of duty couldn't hunt them down and kill them for revenge.