When Mr Weasley takes Harry to the Ministry of Magic via the tube (train), at the begining of the scene they are shown attempting to pass through the London Underground ticket barriers. Mr Weasley first walks directly into the barrier (to create humour in the movie), to which Harry indicates he needs a ticket. He does this by showing 2 Oyster Cards (blue plastic credit cards with the Transport for London Oyster logo on), which he pulls out of his own pocket. Breifly before the footage cuts, Harry is then seen putting the Oyster card in the ticket slot, which is slightly further down than the yellow Oyster card reader on top of the machine. The slots are for paper tickets. Anyone who has been to London knows that the card is waved over the yellow reader to gain access. I know this is only small but I'm sure many of the millions of Londoners, like myself will spot this.

I'm surprised Daniel Radcliffe hasn't travelled on the London Underground before (possibly too famous to do so) but I'm sure he worked it out straight away hence why they cut the scene directly at that moment.