Facebook and mobile don’t go hand in hand when it comes to creating page tab applications. Facebook actually doesn’t show app tabs on mobile at all.
Facebook does work with mobile when it comes to creating Facebook applications.
Page Tab Apps have URLs that look like this: https://www.facebook.com/pagename/app_0123456789
Facebook Apps have URLs that look like this: https://apps.facebook.com/appname/
When creating a Facebook application, you can specify a mobile URL. Then when mobile users hit the Facebook app URL, they’ll be redirected to whatever is set for the mobile URL. This could take users to a mobile version of your website, iTunes to download an app or anywhere you want off of Facebook.
The problem comes into play with page tab apps when you start sharing the URL on people’s wall. When mobile users click on it, Facebook is throwing a 404 Page Not Found error instead of redirecting to the mobile URL.
At this time, it’s hard to know if this is by design or a Facebook bug. Facebook Apps work with the mobile URL, but page tab apps do not; even though that’s not clearly defined when setting up an app. I’m hoping it’s a bug and will some day be fixed, but the jury is still out on that.
I have found a way to work around this though. What you need to do is set up a Facebook App and point it to page that’s only purpose is to redirect the user to the Facebook page tab URL.
Then update any sharing or promotional URLs to share the Facebook app URL.
When a desktop user clicks on a link in their feed, they will then be clicking on the Facebook app URL and the redirect script will take them to the Facebook page tab URL.
When a mobile user clicks on a link in their feed, they will be clicking on the Facebook app URL too and this time Facebook will redirect them to the mobile URL that was setup in the app settings.
It’s a definitely a work around, but it works until Facebook can make page tab apps mobile friendly; which could be in a few hours or a few years.