When Thomas Newton makes a phone call to 911 from a payphone, he properly makes it without depositing money. (Emergency calls are free from payphones in the US.) However, when he hangs up the receiver, change is heard dropping through the mechanism of the phone.
Astrid mentions that Walter is out counting cars to help trigger his memory but says don't worry, he promised not to go on the freeway. New Englanders use the term highway and would never say freeway (a term used in California) for high-capacity roads.
When the first teenager is found dead, no one acknowledges the broken glass on the car. That would be the first indication to inspect inside the warehouse. The reason they take a look, is because of a joint without lipstick. Indicating that the dead girl wearing lipstick, wasn't alone.