lucy24 - 9:50 pm on Nov 15, 2012 (gmt 0)
There are just a few.
A few specific, individual URLs-- or a few discrete categories of error? Have the percents been unescaped by the time they hit htaccess? It's tiresome if you have to say %(?:25)? every time.
What have you got so far?
:: detour to explore nasty suspicion that literal % signs really ought to be escaped, although I've got one RewriteRule that has them unescaped and it doesn't throw errors ::