Not only were the Egyptians thrown into confusion, but they were also given that most aggravating state of affairs: vehicle trouble. Their chariots, those powerful weapons in which the Egyptians trusted for military advantage, became all wobbly in the wheels. In fact, the wheels even came off, so it is no wonder that "they had difficulty driving."
However, the worst was yet to come. For now, to his horror, someone noticed that the sea was beginning to become unsettled and flow back toward Pharaoh's struggling forces.