Plot hole: This happens after Gabe has killed the guy in the cavern and is reaching for the radio. We hear Frank trying to reach them, so they must be on the same frequency. Then, Hal finds out that a bomb has been planted, grabs a radio from the bad guys and starts yelling for Gabe to get out of the cavern because of the bomb. Why didn't Frank hear any of this on his headset?
Plot hole: During the finale you see Stallone's character attach the helicopter to the ladder. He then runs away from the helicopter, and away from the ladder. Even if he does run round in a semi-circle, (unlikely from what we see), they show the helicopter go over his head as he jumps off the hill onto the ladder. The helicopter then pulls the ladder off the cliff face. Based on the length of the helicopter's cable it must have kept going for an awful long distance!
Answer: There are two stunt doubles for Mr Stallone on imdb.com, their names are Mark De Alessandro and Jeff O' Haco. The site doesn't specify who did what.
The-Immortal