I'm not as familiar with Parliament's rules as others, but I'd have thought who could vote in an election was relevant to a bill to hold an election. And the fact amendments might pass the reason why governments don't normally want to call an election in this way.
This is surely not going to turn into one of those sagas which leaves the whole of Parliament, but most of all this PM, looking silly?
All of which doesn't mean I support or oppose votes at 16 or EU citizens voting. Don't have a strong opinion. But if you're going to have a bill for an election these are things that should be discussed, rather than everyone charging in a hurry in whatever direction the whips set
This... (maybe amendments won't get called, but if they do...) 
