Other mistake: When Warwick Davis shows Joe the form he's tricked his father into signing to allow him to transfer schools, the form is shown full screen. The "home" phone number is the same as that used in the school's letterhead, and there is text that says"insert name of fictitious school here." Also in this scene the name of the headmaster and phone number is visible, but none of those details match what is on the school's advertising board a couple of scenes later when Joe starts at his new school.
Other mistake: After a month of suspension, James can finally sell again The Big Issue. The issue he carries in the street though, is issue 1174, from early October 2015. Besides the anachronism, the first issue he was selling, well over a month before, was number 1175. (01:16:00)
Other mistake: When Bill is alone with the girl at his house, there is a roaring fire, but in the next scene the fire is completely out and he comments, "you must be cold, I didn't have time to start a fire".
Other mistake: The typewriter ribbon in Gemma Arterton's typewriter looks to be installed upside down, with the red half of the ribbon showing above the black half.