You're going to have to elaborate if you know any more, it seems incredibly easy to check programmatically.
Hmmmmmm...downloadable 'modules'?
You can't download executable code to an iPhone app outside the App Store, only data.
Curious, how do they know it's executable?
Apps are Turing-complete, right? In theory, that means it's possible to make an arbitarily complex and obfuscated route to a private API, making it impossible to detect via simple static analysis.