Elliot's clip board changes between shots.
In the opening scene, a piece of lettuce disappears from Turk's sandwich between shots.
Carla mentions she never went to college, however she is a RN (Registered Nurse), she had to go to college for two years to be a nurse. Becoming an RN requires an associates of nursing science degree.
When Turk is sitting on the bench in the rain, the shadow of the bus passes over him revealing the back lighting.
When Turk opens the door and enters the room after he has been paged my Kelso, you can see a hand in the bottom left corner, holding the door, preventing it from closing.