When Dan handcuffs Pettigrew to the tower you can see it doesn't match the photo shown in previous episodes.
The weight and power of a moving glacier crushes everything underneath (unless hidden in a narrow crevasse). Hence, a mammoth graveyard could not be preserved under a glacier.
When they perform the lumbar puncture, they insert the entire length of the needle into his spine. This would paralyze the child as the depth should be somewhere between 3 and 4 centimeters for a child his height. The needle they use is at least 2.5-3 inches long (6 - 7 centimeters).