When Mary has the printing run of her study of Asperger's Syndrome destroyed because of Max's disapproval, the local paper headlines "Local Academic Pulps Novel and Career." Her book, however, was a non-fiction, academic study rather than a novel, which is by definition fictional.
When Mary looks through the phone book in the post office, the name reads M J A Horowitz. When she writes the first letter, she writes to M J Horowitz. However, when she mails the first letter, the name on the envelope she posts is "Max Horowitz".
When the story about the character (Max's upstairs neighbor's friend) who buys a Ferrari is told, the car is shown as having right-hand drive. It's extremely unlikely someone in the US would buy a right-hand drive Ferrari, although of course that would be common in Australia where the movie was made.
When Max is seen in court the judge is seen to be wearing a old powdered wig, back dropped by an American flag. This wig however identifies a magistrate operating in a court in a country that is part of the British Commonwealth (such as Australia, Canada, Britain, etc) and is not worn by American judges.