This actually is part of the appstore review process (I do this for my job). However, we've had apps slip through before. I'm not sure entirely why this happens

This actually is part of the appstore review process (I do this for my job). However, we've had apps slip through before. I'm not sure entirely why this happens, since the checks for missing entitlements or incorrect signing should be automatic, but it does on occasion. This is a problem with Apples review process as much as anything else, since you can't test the properly signed release version of the app until you publish it to the appstore for all to see.