During the interior shots of Clyde's truck while driving with the boys, the back window is blocked as if he's carrying a bunch of cargo in the trailer. When seen from the outside, the trailer is nearly empty.
After Captain Marvel picks up the truck, he takes a few steps while carrying above his hands. But as he moves his empty hands are briefly visible.
For interior shots of Clyde driving his truck with the two boys, the truck's gearshift lever is in the "park" position.