During the flyover of the iceberg to take pictures, most of the shots showed a long rectangular iceberg that had high sides and a flat top, but one shot showed a much smaller U-shaped iceberg mostly melted away above the surface.
When the propulsion engine (looks like rocket but runs on fuel from a can like a jet would) began breaking its tether lines, the tether line anchors were pulling and causing the material around them, which is supposed to be an iceberg, to ripple and move, showing it to be made of a material other than ice.
When the missiles hit the iceberg, they are shown from a fixed vantage point twice, from what appears to be looking out through the helicopter window with the window frame framing the shot of the missiles stuck in the iceberg. But the view remained fixed in place, and if it were from the helicopter, which was flying away from the iceberg, the rockets would have been receding and getting smaller.