Steve is floating head first down the river. On the close-up of his face, the reflection of the trees in his glasses is moving as if he were floating feet first.
When the boys are in the cornfield, at first they are all taller than the yellowed-old stalks, yet the next scene shows them shorter than the ripe green stalks.
The ropes used to tie the three Lego Ron Howard to the roof of the car go through the windows, which means the boys would not be able to open the doors.
The guys understand Toshi's Japanese in the cornfield in this episode, when usually they misinterpret it.