After Red kills Matheson with his Daewoo Lanos, he says the famous line "You just got killed by a Daewoo Lanos, motherfucker!" When he says it, he pronounces Daewoo incorrectly; the W is silent and it's pronounced dayoo.
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 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.
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.
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 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.
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.
General Bratt's uniform is wrong for 1937. It is from the 1970s. He should be wearing what was called "Pink and Tans". Additionally he seems to be wearing a marksmanship badge. Officers don't wear these. He is also wearing General Staff branch insignia. Generals don't wear branch insignia. Finally his shoulder epaulet should tucked under his lapel.
In the Trailer "On the hood" the computer in the police car is pulling up data on Dale Denton. After it shows "Wanted for Felony hit and run" it then says "arrest on site". The correct usage is "arrest on SIGHT"
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.
When Red is bleeding in the bathroom after being shot, it may appear that Dale calls Red by the name of Dale. He actually says "I think 'Yes! I'm going to help you, Dale.' That's the answer I'm looking for!" He was trying to motivate Red - he didn't call Red by the wrong name.
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.
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.