During the minefield sequence, Mack yells at Kapp about behaving himself, while holding him by the collar. Then there's a nearby explosion and we cut to a medium shot showing the whole line of people crouching down - and Kapp is back in his place in line. Cut back to the close-up, and he's back crouching down next to Mack.
When rappelling to attempt a second ascent, Betsy Blane has a figure 8 knot secured to her harness with a locking carabiner, but is then seen controlling her own descent. A figure 8 is a fixed point and cannot move it's position along the rope. Rappelling in this manner means someone above her was controlling her descent. If her father, Jonas, was doing this, then holding her hand in a braking position has no effect in controlling her descent.