Question: When David steps on the land mine, the group rescues him by tying a rope around him and pulling while he runs. What exactly does this accomplish? It's impossible to outrun an explosion, much less pull someone to safety at supersonic speed.
Answer: Anti personnel mines usually have a small blast radius compared to a bomb or artillery shell. If they can pull him away quickly enough he can be clear of the blast.
Answer: Yes, I think the blast of a land mine usually goes straight up, unless it's a bouncing Betty.