At one point you can barely hear someone in a crowd of background voices yelling "This movie sucks. It really sucks."
In a wide shot of the plane dragging the purple lightening ball over a mountain, you can spot down in the bottom left corner of the screen, for the first three frames, a tiny image of "The Grinch". Artists snuck it in as a joke, because the mountain looked similar to the mountains from the Ron Howard film.