It's interesting to see the transition from physical models to blue screen based action. The models of the trains and the DeLorean are great and remarkably intricate, whilst the blue screen shots are being used for some of the more difficult flying scenes.
Crazy! Back to The Future was released in mid-1985 and things have changed a lot. The models, the camera equipment... makes you appreciate the film even more knowing how it was put together.
Good times. Now it's all green shit in background.