.htaccess rewrite rule giving server error - .htaccess

Question

I think I just need a second pair of eyes for this as I can't see why i'm getting a server error.
RewriteEngine On
RewriteRule ^Gig/([a-zA-Z0-9_-]+)$ gig.php
RewriteRule ^Gig/([a-zA-Z0-9_-]+)/$ gig.php
#allow non caps
RewriteRule ^gig/([a-zA-Z0-9_-]+)$ gig.php
RewriteRule ^gig/([a-zA-Z0-9_-]+)/$ gig.php
Edit:
I have now viewed the log and the reason is there are far too many internal redirects. I myself am not too competent at mod_rewrites etc so please have a look.
#redirect so home page shows /Home
Redirect /home.php http://localhost/Home
#add php extension
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php
Redirect /home.php http://localhost/Home
# redirect to .php-less link if requested directly
RewriteCond %{THE_REQUEST} ^[A-Z]+\s.+\.php\sHTTP/.+
RewriteRule ^(.*)\.php /$1 [R=301,L]
#redirect www to non-www
RewriteEngine On
RewriteCond %{HTTP_HOST} ^www\.^([a-zA-Z0-9_-]+)$ [NC]
RewriteRule ^(.*)$ http://^([a-zA-Z0-9_-]+)$1 [L,R=301]
#remove trailing slash
RewriteEngine on
RewriteRule ^(.*)/$ /$1 [L,R=301]
#allow artistprofile nice url
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_\-]+)/?$ artist_profile.php
#info nice url
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_\-]+)/[Aa]bout/?$ artist_about.php
#gigs nice url
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_\-]+)/[Gg]igs/?$ artist_gigs.php
#tracks nice url
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_\-]+)/[Tt]racks/?$ artist_tracks.php
#gig nice url
RewriteEngine On
RewriteRule ^[Gg]ig/([a-zA-Z0-9_\-]+)/?$ gig.php
That's all the rewrites in the .htaccess file
Edit:
The problem is the adding PHP extension part
#add php extension
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php
I think its due to the ([a-zA-Z0-9_-]+) being after the file name.

Answer 1

You need to escape your - characters when they're inside brackets. You can also shorten your code to the following:
RewriteEngine On
RewriteRule ^[Gg]ig/([a-zA-Z0-9_\-]+)/?$ gig.php
# Escape it! ^^
Why can we shorten it like this?
[Gg] means "The character G or g"
/? means "/ repeated 0 or 1 time"