Edit: try this
PHP Code: 
RewriteRule ^file/([^/]+)/?$ script.php?fileName=$[NC,B
I have just tested above, worked...

Reference: [B] Flag , you might also need [QSA] Flag
mRAza Reviewed by mRAza on . PHP problem handling urlencoded '&' (%26) char Hello all, A script we are working on deals with passing file names in the URL (via $_GET). Some files contain the '&' symbol in the name. & is the separator in PHP to identify the new $_GET variable. We typically use urlencode($theString) to encode 'funny' characters to be URL safe. However, PHP seems to treat the encoded '&' value in exactly the same way as if it were not encoded. Here is an example of the problem. Rating: 5