Continuity mistake: When Will is sitting on the kitchen counter upset, he is eating butter biscuits from a tin, with the tin and the tins lid on the counter next to him. Then his mum comes in and they talk and at the end of the scene they hug; but now the biscuit tin lid has vanished although nobody touched it. (00:17:00)
Continuity mistake: Shortly after arriving at their mother's house, Will's brother, Sam, nervously excuses himself from a conversation with Grace. "Excuse me," he says, "I have to go get a ladder. There's a couple of bulbs out in front, and now it just says 'Happy Ho-days.'" However, exterior shots of the front of the house show no holiday lights whatsoever.
Continuity mistake: When Grace and Sam are up in the attic sitting on beanbags and talking across a makeshift table, Grace's champagne glass is placed right in front of her. Yet in one shot the glass moves to the other side of the 'table' and then back to its original place in the very next shot. (00:19:00)
Continuity mistake: When Grace sits down at the counter in the kitchen as Karen talks to her, she puts her water bottle down and it's lid is firmly screwed on. In the next shot as she begins to tell Karen about her and Sam's fumble, the lid is off and is nowhere to be seen. (00:14:10)
Continuity mistake: When Grace and Sam are in the kitchen with Marilyn, after their fumble in the attic, they are both holding water bottles. In the first shot, as Marilyn begins to say "Well let's look again because I know...", Sam is holding his water bottle at his waist. In the next shot as she finishes, saying "...it's up there", Sam is instantly drinking from the bottle. (00:13:40)