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.
Character mistake: In the movie it is stated that "There are 159 million, million, million possible Enigma settings. All we had to do was try each one. But if we had 10 men checking one setting a minute for 24 hours every day and seven days every week, how many days do you think it would take to check each of the settings? Well, it's not days; it's years. It's 20 million years." This is massively understating it - if it would take 10 men only 20 million years to check all the settings of Enigma they would have to each check 251,861 combinations per second. (00:15:04 - 00:16:46)
Suggested correction: It's not a plot hole, it's how they operated it in reality.
I have a copy of British Intelligence in the Second World War, by F H Hensley (the official historian and ex-GCCS). I quote page 309 as an example - 'the knowledge of the Tracking Rooms was far from perfect on account of delays in breaking the settings...During the first half of 1943, however, while the traffic was read with delays that were sometimes less than 24 hours, days when the settings proven to be unusual stubborn were not uncommon...Between 10 March Andy the end of June the setting standards for an a further 22 days were either not broken at all or broken only after a long delay.'...'A delay of as much a said three days in learning that U-boats had been ordered to move to new position so could thus mean than intelligence was received too late to be of use in diverting convoys'. So pretty clear that they carried on attempting to crack the settings well after the end of a day so they can process intercepts which might still be relevant.