Continuity: When United 93 is in the air, the terrorist in the back of the plane has his brown jacket alternately zipped/unzipped between shots.
Anachronisms: The UPS airplane shown on the tarmac at Newark Airport is painted with UPS's new logo, which was not introduced until 2003.
Anachronisms: In an early runway scene, a billboard for the film Chicken Little (2005) can be seen in the background.
Continuity: After takeoff, an exterior shot of the plane switches from a Boeing 757 to an Airbus A320.
Continuity: United 93 is cleared to depart from runway 4L at Newark. However, you can see the terminals out the right side of the aircraft, indicating that it is departing to the southwest, on runway 22R.
Continuity: During the flight, the terrorist with the bomb strapped to his waist, his shirt appears unbuttoned and then buttoned again within the same scene.
Continuity: In the Boston ATC sequence, the radar screen shows American 11 at a flight level of 350 (35,000 ft). This alternates with a flight level of 310 between shots.
Revealing mistakes: As Flight 93 begins its takeoff roll, only one of the passengers seems affected by the acceleration. Just one of their heads is against the headrest.
Audio/visual unsynchronized: When auditing the recording of a transmission from American Airlines Flight 11, the reviewer repeatedly listens to the crucial portion, rewinds the tape, and listens again. But as the sounds play, the reel moves only a small fraction of a turn, while the rewinding covers several times that distance; yet the reviewer supposedly always ends up back at the same point in the recording.
Errors made by characters (possibly deliberate errors by the filmmakers): During the take off roll, the curtain that divides First Class and Economy class is closed. This is in breach of FAA regulations that state the curtain must be stowed for taxi, take-off and landing.
Revealing mistakes: When the hijackers force the air hostess to knock at the cockpit door, the little knife bends at a serious angle under the chin of the woman, indicating that it's rubber. (about at 1:01:41)
Continuity: Boston Air Traffic Control Center refers to American Airlines flight 11 and United Airlines flight 175 as 'American eleven' and 'United one seventy-five', but New York Air Traffic Control Center refers to the United flight with 'heavy' succeeding the call-sign, although both aircrafts are Boeing 767-200s.
Continuity: During first officer's preflight walk around, the aircraft has Rolls-Royce RB211 engines. In fact, all United 757's are equipped with two distinctive Pratt & Whitney 2040 engines. The engines alternate between Rolls Royce and Pratt & Whitney during exterior shots of the 757.
Anachronisms: The United Logo at the Gate is the new United Logo. It was not United's Logo in 2001.
Continuity: In one scene the hijacker flying the plane puts it into a steep dive but when the camera shows the passenger cabin the plane appears to be angled upwards as if in a steep climb and the hijacker watching the passengers from near first class if leaning backwards (towards the cockpit) to maintain his balance also indicating a climbing deck angle.
Continuity: When the captain turns off the fasten seat-belt sign, the stewardess walks through the closed curtain, turns and closes it again, says her line at the front of the plane and turns back towards the curtain which is now fully open.
Revealing mistakes: The hijackers in the film speak with very notable North African and Iraqi accents which are quite different from Saudi and Lebanese accents.
Crew or equipment visible: During the final scene of the movie, where the cabin is inverted upside down and the oxygen masks eject from the ceiling, you can clearly see that some of the cabin ceiling panels are missing and you see tubes and wires in light blue and red colors revealing the set.
Factual errors: In several scenes, the altitude indicator ("artificial horizon") shows the aircraft in a climb, while shots through the windscreen show the aircraft in a dive. The scene is shot at a downward angle furthering the illusion of a dive.
Factual errors: One of the air traffic controllers makes references to an "Alaskan" Airline flight. Any air traffic controller would know that the name of the airline is "Alaska" (with no "n").
Continuity: When the stewardess goes forward she closes curtain dividing first class and economy. When she turns around and goes back down the aisle, the curtains are completely absent [near 39:40].
Anachronisms: In the scene prior to Captain Dahl announcing a delay in take-off, an Air Canada plane is shown taxiing behind Flight 93. It's an Embraer Jet which the airline first started flying in 2005, in a color scheme was first introduced in 2004.
Anachronisms: Near the beginning of the movie a car arrives to the airport. The shot from the inside of the car reveals an inspection sticker on the windshield that expires in 2004. The latest an inspection sticker could expire (in the real situation) would be 2002.
Errors in geography: When United 93 enters Cleveland Air Traffic it says Cleveland, Ohio, yet, the Cleveland Air Route Traffic Control Center is located in Oberlin, Ohio. Some 35 miles southwest of Cleveland
Continuity: Once the passengers on the plane are hearing of the WTC attacks, the stewardesses at the back start hearing the passengers talking and start reacting. However, between shots, the positions of the stewardesses change very noticeably. One is in front of the rest of the stewardesses at the back listening to the passengers but in the next shot, she's in the far corner tucked up against the door of the plane hiding. In the next shot, she's back to her original position.
Errors in geography: The green "running man" EXIT signs in the terminal and jetway are not used in USA - these shots were probably filmed in the UK
Continuity: Near the end of the movie, when the passengers are fighting for control of the plane, the main stewardess is shown in many shots as the passengers move to the front. Almost each shot of her shown has her hair is arranged in a different way.
Factual errors: Despite the aircraft being flown manually, on the Primary Flight Display in some of the scenes, "CMD" text is still present (possibly taken from another aircraft). It means the plane is still under the control of the autopilot.
Factual errors: Shortly after the takeover of the cockpit there is one shot of the indicator of amount of fuel in tanks. The tanks are empty.
Factual errors: During the overview of the Newark airport in the beginning, an air-traffic controller can be seen wearing a blue lanyard displaying, "Transportation Security Administration" with an American flag displayed after "Transportation". These were issued post-September 11, 2001 as the Transportation Security Administration was formed under the Aviation and Transportation Security Act, which was signed into law on November 19, 2001. Most 2001 roll-out supervisors at the TSA have these lanyards for airport identification cards. An ATC could own a lanyard as it is understandable that the lanyards would be distributed throughout the airport operations personnel.
Errors in geography: Various goofs exist at the start of the movie while the passengers are arriving at the gate at Newark Airport which reveal the shooting location to be the domestic departure gates at Stansted Airport, Essex, UK. These include the BAA signage, the seating at the gate (17), the rail link to the international departure gates (seen through the glass at the security checkpoint) and a "2 for £25" advertisement on the passenger walkway towards the gates.
Miscellaneous: When Ben Sliney enters the control room the title 'National Air Traffic Control Center' is shown. The correct name is 'Air Traffic Control System Command Center'
Factual errors: A number of passengers are seen making phone calls from cell phones, but in reality, only two people made calls from cell phones during the last few minutes of the flight - Edward Felt and CeeCee Lyles. All other calls came from in-flight phones.