In the beginning of the film when the private is smoking a joint, the camera cuts to outside of the box he is sitting in and you can clearly see the smoke from a smoke-machine blow towards the private.
When Dale first visits Saul to buy pot, the tray on Saul's table has two empty silver canisters. When Saul returns with Dale's Pineapple Express pot, they reach for the cross joint and one of the canisters is filled with pot.
The day Saul and Dale wake up in the woods is Daylight Savings Day, which is always on a Sunday. However, Dale visited his girlfriend's high school the day before which should have been Saturday when it should have been closed.
When Dale and Saul are at Red's house and they're talking about Red's supposed herpes, Saul is pointing to Red with his right hand. When it cuts to Saul explaining how Red must have gotten it from eating a lollipop out of a stripper's snatch, he's pointing at him with his left hand.
When Dale and Saul are sharing the "cross joint" near the beginning, they each smoke a different joint. The joint that Saul smokes is obviously thicker than the joint that Dale smokes, but they are acting like they are sharing a single joint.
While Dale is on top of Red with the door, they keep jumping from place to place on the floor. First, Red's head is in the sink, then its next to the sink, then farther, then closer. Even the sink itself jumps from sides that it fell on. Sometimes it's on its back, sometimes not.
When General Bratt descends down the ladder to the secret lab, a soldier stands in the background holding a rifle upward. The rifle changes positions from straight up to an angle as the camera cuts to a wider view.
Ted Jones has no connection to Dale until Saul tells Red Dale's full name. The degrees of separation only lead him as far as Saul. Therefore, Dale and Saul could have just hidden out at Dale's apartment from the very beginning. However, Dale can't be certain that the murderers didn't see him or his license plate, so it makes perfect sense that he'd want to stay away from his apartment.
Budlofsky and Matheson have never seen Saul, nor has Saul seen Budlofsky or Matheson before they see each other with Bubbe, so they shouldn't recognize each other by sight. However, the context and behavior of both parties makes it easy to guess each other's identities on the spot.