Visible crew/equipment: When Rex Linn is looking at his tracking monitor before he shoots at the rabbit, we see a shot of the screen, with a reflection of the camera lens in it.
Visible crew/equipment: When Hal and the bad guys come across the two goofy base jumpers at the top of the mountain, you can see the whole camera crew's reflection in the sunglasses of one of the jumpers.
Visible crew/equipment: When Stallone is sliding down the slope with the bad guy, and the bad guy goes over the cliff into the darkness, you can see the flaps of the air bag or net flail about when he lands on it - most noticeably on the left side of the screen. (00:56:25)
Visible crew/equipment: When Frank gets shot the shadow of the camera can be seen on his back.
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