When Gregory is making the bed in one of the first scenes, he opens the three windows in the room before leaving. When John enters the same room shortly after, while Gregory and Ramon are swimming, the windows are closed.
The amount of milk in a bottle does not match the amount of milk on the floor after the bottle is dropped and broken.
The action takes place in the Northern Hemisphere, over Memorial Day, yet a character mentions seeing the constellation Orion, which is not visible from there at that time of year.
The play's theater company is mistyped in the credits as "Manattan Theatre Club"
When Buzz Hauser (Jason Alexander) is singing along with his CDs on the bus, he screws up the lyrics to "Wilkommen," from "Cabaret." Anyone as much of a theater queen as Buzz is would never screw up those lyrics.