Here are my answers to questions posed on a online forum for Christian filmmakers (I assumed we were using the term "'Christian' Film" in a philosophical/world-view sense rather than a marketing sense):
1. What is a "Christian" film?
A film that purposefully (not accidentally) tells the truth without defiling* the cast, crew, or audience.
2. What elements should a good Christian film have?
The truth. (John 8:32)
3. What elements should a good Christian film NOT have?
The lie. (Romans 1:25)
*"defiling" is not synonymous with "offending" or "challenging"