When Morgan, Jeff and Lester are trying to open the door and escape, the store hours written on the door are backwards to anyone standing outside, making them useless.
When Big Mike bowls over the Fulcrum agent at the Buy More, we are treated to several slightly slo-mo views of him crashing into a display of merchandise. The first side view shows his handgun knocked loose and flying right past the camera. (It also reveals the safety padding under his tee shirt.) The front angle shows no gun. The rear angle then shows the gun in his hand and the final front angle also shows the gun.
During the opening Ferris wheel scene, Jill's watch clearly shows the time as 3:30, despite the scene being filmed at night.
When Chuck is explaining to "Leader" how he locked down the Castle and that they're protected from him due to the bulletproof glass, several round holes are clearly visible in the glass, probably meant as air holes. Leader could have easily shot them through these holes.
When the Gravitron starts spinning, Chuck and the fulcrum agent are thrown into the wall showing a high amount of centrifugal force. The fulcrum agent loses his gun and it falls to the floor. If the Gravitron was truly spinning at that speed, the gun would also be pinned against the wall.
During the first television broadcast of this episode, Morgan could be heard calling Ellie "Sarah" as she is throwing away test turkey #1. This was edited out for future broadcasts.