When Mitch is walking to work on his 40th birthday, he passes by the Ed Sullivan Theater, which prominently displays a sign for the Late Show with David Letterman. Since Mitch was born on September 8, 1952, that would make the date September 8, 1992. The Late Show didn't premiere until August 30, 1993.
After duke saves Mitch, Phil and Glen from the two cowboys they rented the equipment from duke cuts the ropes on their hands and Mitch says "Curly were so sorry we thought you were dead". However his mouth does not move.
At the very beginning of the movie, Mitch gets up at 5:16am, goes jogging with his "cow", then commutes by train from his home in New Rochelle to downtown Manhattan and arrives to work at 6:07am (see clock in background over his head). Can't be done.