The airplane shots at high altitude show a red vertical stabilizer. The airplane on the tarmac and taking off and landing has a white vertical stabilizer.
When Barney picks the deadbolt lock into the baggage room, there is no deadbolt visible when the door swings open as viewed from inside the room.
The tape recorder changes to a different one used for the 'self destruct' effect; this can be seen by the addition of a dent and the lack of a capstan sleeve rest on the smoke effect machine.
The air vent in the cargo hold switches between fully open and partially open between cuts from the vent and the characters.
The tape recorder is on a background upon which a perforated metal plate appears between shots.
Just prior to the first landing, Barney holds up the altimeter and it shows the plane descending from about 18,000 feet. Since the cargo hold is now pressurized with the cabin (8000-10000'), Barney's handheld altimeter should read the pressurization, not the outside altitude.
Barney and Rollin are in the baggage compartment of the plane and are running out of air. Barney drills what appears to be a 3/8 inch hole into the main plane and immediately they have enough air. A hole that small would require at least half an hour to allow enough air in to make a difference.
When Martin Landau (Rollin Hand) and Greg Morris (Barney Collier) are hidden (under already clearly tight and uncomfortable conditions) inside trunks into which no air holes have been drilled.
Trubner's name is misspelled as "Traubner" on the all-important piece of microfilm.
When Barney Collier is at the baggage claim door there is a handle and a deadbolt, which Barney picks. Inside, it can be seen that there is no deadbolt on the inside of the door.
During the second takeoff of the airplane, with the 'No Smoking' sign lit, Cinnamon is shown smoking a cigarette.
When Rollin is rehearsing the chancellor's voice, he is seen speaking all during the time the voice is supposedly being played as output from the tape recorder.
When Jim opens the door of the Rolls Royce at the end, you can see the crew reflected in the door.
When the Kurzon automaton is ejected from the aircraft, a mattress is clearly visible for the actor to fall onto.
In astrology, a person born at sunrise would have the same ascendant as their astrological sign, but Cinnamon says that the chancellor is a Sagittarius with an ascendant of Cancer - two almost diametrically opposed signs. Whether Cinnamon believes in astrology or not, the character she's playing does, and this is a mistake she shouldn't make.