Continuity mistake: During the chase, when Bill Hickman drives the Charger into the residential area, as he loses Bullitt he comes to a distinctive intersection: he first looks right, then left. As he looks left, the first view of the sky shows it is half full of light clouds. A moment later, when the car drives on, the sky is completely clear of clouds. There are other shots showing even heavy clouds/blue sky, too.
Other mistake: Just before the Charger crashes, a tow bar connecting both vehicles is visible on the Mustang's front bumper.
Continuity mistake: In the leadup to the chase, the Charger stops at the top of a hill and the occupants look left where we see a green car parked in front of a red car. As the Charger pulls away we get the same view. The red car is still there, but now has a blue car of a different model in front of it and in a different place.
Answer: Airport security in the late 1960's was not nearly as thorough as it is in present day. Metal detectors didn't become commonplace at airports until the early 1970's.
BaconIsMyBFF
It was the D.B. Cooper hijacking of a Boeing 727 commercial jet in 1971 that radically changed how airport security was handled. Before that, there was virtually little to no pre-boarding security checks.
raywest ★
In the 60s, my dad would take my brother and me to the new Oakland Airport to watch planes. There was nothing to stop us from walking through the entire terminal. The original terminal was a small building with a 3-foot tall chain-link fence separating spectators from the boarding Constellations, Electras and DC-6 planes 80 ft. away.