During Jamie's story of his relationship with Amanda to Megan his wineglass goes from half-full to empty in less than two seconds, while he's speaking.
When Jamie (Michael J. Fox) runs from his brother who's been waiting for him on Jamie's stoop, he enters the Christopher Street station of NYC's 1 train. But when the camera shows him on the subway platform he's actually at the 42nd Street/Times Square station.
Tad tells Jamie they're going to a party on Staple Street. There's no such street in New York City.