So, we have 2 million people in 400,000 carts with 4 million animals. Let's give an average spacing of roughly two meters per person and animal, such that each individual is at the center of a square (for the sake of simplicity) four meters on a side, or 16 square meters. We'll roll the carts into this (no pun intended) so all we'll count are the animals and the people. This entourage takes up an area of 96,000,000 square meters. As there are 1 million square meters in a square kilometer, this comes out to 96 square kilometers, or a box roughly 10 kilometers by 10 kilometers.
I doubt, however, that the Israelites are working their way across the desert in a square. Asphalt mentioned that he believes the Red Sea parted a distance of two miles (3.2 kilometers). We'll say our column is three kilometers across, which would make it 32 kilometers long (about 20 miles). It would cover about its own length every day, but communication between the head and tail would be problematic, and it wouldn't be fun to be tail-end charlie (not after 6 million people and animals had passed before you).
On a more practical note, it would mean that the Red Sea stayed parted for more than a day while the Israelites crossed.
Since none of that actually happened, perhaps we should be looking for clues of a smaller, tribal-sized exodus.