If you ever use, or intend to use, rewrites in the future (or if any of your other rules found in the .htaccess file use RewriteRule already) change the method slightly.
Instead of using Redirect or RedirectMatch, use RewriteRule with the [R=301,L] flags. It is important that all of your redirect/rewrite code belongs to the same Apache module.
To be clear, RewriteRule comes from Mod_Rewrite and Redirect and RedirectMatch come from Mod_Alias.
Execution order of your directives is controlled NOT by the order the code is listed in your .htaccess file, but by the module execution order within .htaccess.
That is, if Mod_Alias runs before Mod_Rewrite, your Redirect and RedirectMatch directives would be executed before your RewriteRule directives (good!) BUT if Mod_Rewrite runs before Mod_Alias, your RewriteRule directives would be executed before your Redirect and RedirectMatch directives (bad!).
The effect of that would be to expose rewritten filepaths back out onto the web as new URLs, to create unwanted redirection chains, and generally not work as expected.
You don't have control over the module execution order. Your host has set that up. Most get it right, but a few do not.
You can protect yourself from the problem now and in the future by using RewriteRule for all of your directives.
You can also take advantage of the very powerful pattern matching controls that RewriteRule has to offer. Be aware that RewriteRule sees only the 'path' part of the URL. If you need to examine the requested hostname or parameters or the original HTTP request itself, add a preceding RewriteCond to examine the required attribute.
In general,
Code:
RewriteRule ^some-pattern http://www.example.com/somepath [R=301,L]
is the way to go.
If you use rewrites make sure that ALL of your redirects are listed before those. This is because the redirects send the user to a new URL, and rewrites 'translate' a URL request into a different internal server filepath. Once rewrites have executed and are looking on the server's hard drive for the content it is way too late to be trying to alter the URL the user sees in the browser address bar.
Redirect first so that user sees the right URL. Once the user sees the correct URL, and only then, execute the rewrite to fetch the content.