Corrected entry: In the scene where Violet, Klaus, Sunny, and Aunt Josephine are leaving Curdled Cave after Klaus figured out the code from the "suicide note", you can see a lighthouse in the background. The light from the lighthouse moves around the side of the lighthouse that is facing the children and Aunt Josephine. It takes about 2 seconds to do this. Then the light goes around the back, and it does not reappear for around 6 seconds. The light should take the same time to go around the front and the back.
Myridon
23rd Jun 2005
Correction: Lighthouses do not have a single light that spins at a constant rate. They are designed so that each individual lighthouse has a different pattern, so that lost boats can identify which lighthouse they are looking at by the changing intervals between the flashes.
Myridon