Somewhere one the "edit movie title" page, I could add links "add episode", where you could enter number and title of each episode.

When the vehicle page is displayed, the site searches in the "movies" table the title of the movie with the number stored in the vehicle info.
It could at the same time search in the "episodes" table a title with the episode number matching the one of the vehicle info (well, actually movie number + episode number).

It is hard to try to explain with simple words such database concept actually. It sounds logical for me as I am programmer, but I guess that it is not so easy for non-programmers.