Corrected entry: In the scene on the plane during the lightning storm, the lightning is flashing brightly directly outside the planes windows. They are at cruising altitude at this point, and although thundercloud tops may be nearly this high, the lightning comes out of the bottom of the clouds, and wouldn't be flashing through the windows into the plane cabin.
Disney-Freak
24th Sep 2005
Correction: Actually lightning comes from the ground up. So yes the lightning could be seen through the windows.
Disney-Freak