In the movie ET(1982), at the near beginning of the film ET is left behind by his spaceship. He simply couldn't fly up to get back to it and he stayed on Earth as seen below:
We see in a later scene that the boy is riding a bike with ET in the front basket as shown below:

How is it that ET couldn't fly to get to his ship at the start of the movie and here he suddenly can fly on a bike?
