The original shooting schedule was 20 days but it abruptly had to be reduced by 4 days only a week before principal photography began. The entire film was shot in only 16 days and split between Northern Ireland and Belgium.
The bus ride at (45:40) features cameos at the back of the bus of the kids' real mothers.
Sarah's apartment was entirely built from scratch on a set in a studio in Belgium.
The car crash sequence didn't quite work on the first take -- typically the only take a small independent film can afford -- so they managed a second one by shooting around the dents.
They taught young McCauley to say "bitch" for a single line, but she proceeded to say it all day long until she apparently forgot it.