There is a poster of The Shins in Kim's dorm room. The band was featured on the soundtrack for Zach Braff's directorial debut film Garden State (2004).
When Michael comes home after the party with Kim and gets into a fight with Jenna, when she asks him "what will happen 10 years from now?" she speaks with her Australian accent.
They find out the sex of the baby. Shortly after, she announces she is 3 months. Normally, you cannot find out the sex of the baby until 20 weeks, 5 months.
When Casey Affleck is hiding in the bathroom from his wife and crying baby, he reaches to open the door with his left hand, thus pulling on the door it should open from the left, yet the camera cuts and the door opens from the right without switching places.