Or HaChaim on Exodus 14:28/אור החיים על שמות י״ד:כ״ח

1 לכל חיל פרעה, Pharaoh's entire army, etc. This refers to the fact that the chariots and their riders who were unable to speed up slowed down the infantry which was marching behind the cavalry. The waters simply covered them wherever they were so that not a single one of them escaped.