(at around 1h 8 mins) After Jude's death, Emily runs up a flight of stairs, seen with the sharp tool she used to stab Travis with. When she exits the stairs and enters the hallway, she is empty handed.
(at around 22 mins) When Jude wants to open the bottle of nitrous gas, Scott prevents him, claiming it is flammable. Actually nitrous oxide is a non-flammable gas.
(at around 39 mins) Cerebrospinal fluid shown in the lumbar puncture (spinal tap) which the doctor performs is yellow. However, in a healthy individual it should be colorless.
(at around 32 mins) When the girl answers the phone at the nurse station, she does not depress the lighted line button. This was necessary on these types of phones. As it sat with no line depressed, she would have had no connection.
(at around 1h 8 mins) A brief glimpse of a wall sign as Emily runs up a flight of stairs shows the letters to be backwards, indicating that the shot was reversed.