At the end of the movie one of Nick's eyes is blue and one is brown. When they show him again from the side the other eye is blue.
When Kaela is using the VR unit to control Flyboy, she uses one hand to flip off Karl, but Flyboy uses the other, even though she is supposed to have complete and exact control over his body.
At 51-minutes in, Sweetie informs Dr. Evers that the object is "a three-dimensional shell encasing the ninth-dimensional matter". A lower-dimensional object cannot encase a higher-dimensional object. For example, a point (0D) cannot encase a line (1D), which cannot encase a square (2D), which cannot encase a cube (3D), and so on.
In two separate scenes, Penalosa and Lund and, later, Vanzant and Evers are shown having sex in zero gravity. This is impossible due to the lack of friction and gravity and requires a third person to hold them in place.
When Karl Larson is describing the death of his father caused by an aneurysm he says the death was fast. However, in the same monologue he talks about a conversation with his father as he was dying, making it sound like the death spanned a much longer time.