Factual error: When the Russian tank rolls up to the two gas pumps, the crew have a choice of regular gasoline (as indicated on the pump), or Good Gulf (a premium gasoline). And in fact one of the tankers tells the attendant, "Gasoline." The trouble is, all Soviet tanks, from the T-34 up through the T-80, have diesel engines for safety reasons. (00:46:55)
Factual error: In the opening scene of the movie, the Soviet paratroopers are seen wearing smooth, black, leather parachute helmets. But Soviet Paratroopers have always worn tan, cloth parachute helmets with ridges that resembled tanker helmets. (00:05:00)
Continuity mistake: After the helicopter attack where Toni and Robert are killed, the Russian helicopters land about forty feet apart, the officers get out and walk to meet each other at the halfway point. For the rest of the scene, they are right next to one of the helicopters. (01:38:30)
Answer: It was a tracking device which gave away their location. Since they couldn't remove it, they decided to kill him as he was now a liability.
Gavin Jackson
They killed him because he betrayed them.