After Sam hires Nick to work in the bar, you can see a glass on the table and a bowl of pretzels. In the next scene when Carla walks into the bar, it is supposed to be three weeks later, yet the glass and bowl are still there.
Alcohol burns with a small, nearly invisible blue flame. The tall yellow flame on the glass of alcohol that Nick holds his hand over is more in keeping with a glass of lighter fluid.
When Sam and Diane try to convince Carla to follow Nick in Sam's office you can see the boom mic lowering down ( in the upper left corner time index ~ 19:50)
Nick suggests to Carla that they go to White Castle and get some hamburgers which would be rather inconvenient as there are no establishments of that non-national chain restaurant in all of New England.
Carla tells Nick about the last man who knocked her up and ran out on her, but she was the one who refused to marry the eminent psychiatrist who was in love with her. As the dejected man left, he promised to provide financial support for the baby, so she was not dumped as she said.