At the end of the movie, during the book signing scene, we can see the Complete Discworld Atlas of Terry Pratchett behind the father of James Bowen and his wife. It's a mistake: the scene takes place in 2012 and the Atlas was published in 2015.
James & Bob catch the 38 bus (a real bus route) from his new flat somewhere in Islington, which is in north London, to get to Covent Garden in central London. This is a journey of approximately 2.5 miles in a southerly direction on this route (presumably James gets off around Cambridge Circus and walks the few hundred yards to Covent Garden). The final destination on the front of the bus should therefore read 'Victoria Station' if it is heading south but in the film the front of the bus says the 38 bus terminates at 'Angel Islington' which indicates that the bus is travelling northwards and therefore in completely the wrong direction.