After Nick gets punched in the nose, in later scenes his wound suddenly heals with no sign of any injury.
Trains from New York to Boston leave out of Pennsylvania Station, not Grand Central.
After Brooke has missed her train at the beginning, there is an announcement that, "Due to Port Authority security regulations, the station is now closing." However, she is at Grand Central Station, which is part of Metro-North. Metro-North and the Port Authority are two different agencies, with no regulatory overlap.
At 40:16, Brooke has no lip movement when she is talking on the phone. Her phone calls are montages of shots showing her speaking and emoting without speaking.
When Nick is playing his trumpet in the subway, the sound is that of a muted horn but the visual shows no mute in the trumpet.