When the gang lands in North Dakota the college kid that Frank drugged is taken away by an EMT, in the following scene when Mac is talking to Charlie and Dee the kid can be seen still in his seat taped to the chair.
The t-shirt that Dennis wears in the hold is different from the one he's wearing when he informs Frank about his conquest in the hold.
The score on Dennis' t-shirt shows 20 beers consumed, yet the next scene that shows the challengers tally, he is listed as having consumed 19 beers.
Mac tells Charlie they're on a DC-10. The set they're using for the plane has 2 aisles with 2 seats on the outside and 3 seats in the middle. However, a DC-10 has two aisles with 5 seats in the middle and 2 seats on either side of the aisle. Furthermore, DC-10s have over 35 rows of seats. The set has 16 rows of seats.
Frank and Dennis appear to be seated in rows 15 and 16 as seen when Mac intervened in their side bet talk. When discussing the women that interest them Dennis mentions the 44th row which is located only a few rows behind him, and Frank mentions the woman in the 33rd row which is a few rows in front of him.