Question about "?"

[RODBUSTR]

     Why is It disallowed in naming film?

[100Coogn]

Probably a Windows thing.  Invalid Character.

Coogan

[Lusche]

Probably a Windows thing.  Invalid Character.

Coogan

Exactly. It's not just a title but it's an actual filename, so it has to follow windows naming conventions.
If you want to go into detail about those: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247

Use any character in the current code page for a name, including Unicode characters and characters in the extended character set (128–255), except for the following:

    The following reserved characters:
        < (less than)
        > (greater than)
        : (colon)
        " (double quote)
        / (forward slash)
        \ (backslash)
        | (vertical bar or pipe)
        ? (question mark)
        * (asterisk)

[Kanth]

because these characters have special meaning to windows OS. Which means windows might think these characters are a directive to it to do special processing instead of just a character.

If you look at an example like sql injection (sort of the same type of concept), you can see how this type of accidental (or even malicious) processing can be dangerous.