Mrs. Harrigan mentions to Briscoe and Logan that her husband planned for a "hockey scholarship to Dartmouth or Cornell" for their son. Ivy League schools do not offer athletic scholarships.
When Logan & Briscoe are checking on Tom Harrigan's at the NY Transit Authority, they are told Harrigan was walking the "J Line". When they go talk to Harrigan, it has changed to the "L Line".
A suspect said he left the gun on the subway tracks of the 7 train, "near the Brooklyn Bridge station". The 7 train does not stop at, or anywhere near, the Brooklyn Bridge.