Continuity mistake: When the contact pulls over and lets Christmas out of the truck, the truck is parked next to some green vegetation. When the truck pulls away it's in a completely different spot. (00:34:40)
Continuity mistake: When Christmas is walking across the street just before he see's the army, he is holding on to his camera. Angle change and his hand is no longer on the camera. (00:20:00)
Continuity mistake: When Christmas hands his passport over on the island for the first time, the way the customs officer grabs it differs between the CCTV footage and the actual camera angle. (00:27:00)
Continuity mistake: When we see Barney pull into Tool's garage, his truck is 3/4 into the garage. When the shot changes, it's only just entering the garage. Note the shadow on the bonnet of the truck. (00:22:30)
Continuity mistake: When the pirate is following the laser sights on his hands, the dots are changing positions massively between shots. (00:04:50)
Revealing mistake: When the pirate leader holds his hand up looking at the laser sights following it, his palm is facing away from the expendables, but the red dot still appears on his palm. (00:04:50)
Continuity mistake: When Barney pulls up at the lights in the pick up the following car is right behind him, cut to a front shot and the car behind is a fair way behind and we see it pull up behind a second time.
Continuity mistake: When Christmas sets up the guns on the front of the plane he turns to Barney raising his right hand. As he turns back in the close up he starts to lower his left hand, this is a continuous scene.
Continuity mistake: Christmas fires the flare from the left side of the plane. In the following shot, the flare appears to be coming from the right hand side of the plane. (00:00:25)
Revealing mistake: When Christmas is filming the army, you can see the switch on the camera is at the "Off" position. (00:29:30)
Continuity mistake: At the end when Christmas and Tool are having a knife throwing contest, the way Christmas is holding his 3rd knife changes between shots. (01:33:40)
Continuity mistake: Throughout the car chase between Barney and Gunner, the damage to Barneys truck keeps changing instantly.
Continuity mistake: When Barney stops at the traffic lights just before the car chase with Gunner, the car behind them slows down and stops. When the camera changes angle the same car is seen from a distance slowing down and stopping again.
Continuity mistake: When Barney is driving his truck away from Gunner his windscreen gets shot to hell. In one shot however all the bullet holes disappear.
Continuity mistake: Barney climbs into the plane as it taking off, however he runs up to the cockpit as soon as he is in. Camera cuts to show the outside of the plane, and the door is now closed. (00:42:00)
Other mistake: When Christmas starts the plane up when leaving the island the first time, he doesn't cut or loosen any of the mooring lines. However he takes off without a problem.
Continuity mistake: When Barney is driving Sandra's truck there is a shot of it sliding through an open area. Camera cuts to Sandra saying "How can you leave?" If you look out the window they are now driving down a residential street. (00:38:40)
Continuity mistake: When Christmas says "If we get out of here it'll be a miracle", he is sat properly. Camera cuts and he is leaning forward with his arm behind his back. (00:38:15)
Continuity mistake: When Christmas and Barney get into the fight when the militia are trying to take Sandra, Christmas uses a throwing knife to kill several men, however in most of the shots, but not all, there is no blood on the knife whatsoever. (00:37:00)
Continuity mistake: When Christmas asks Sandra if they are close, he is sat facing her in the tuck. Camera changes and he is now facing the front. (00:34:50)
Answer: The back stories of the individual members of the team have never been elaborated upon. It is never stated where the members received training.
BaconIsMyBFF