Plot hole: There is no logical reason to switch off the Bombe at midnight when the codes change. Firstly, Turing's proving the concept of automated code breaking, so even if it only finds the right settings days or weeks later, the experiment is worth doing, then you can work out how to speed it up to be operationally useful. Secondly, even in steady state operation, cracking "yesterday's" settings (and thus intercepted signals) is still going to be pretty useful in most cases. Threatening to smash the Bombe up at midnight is good stuff to add some movie tension but, in reality, it's nonsense.