Plot hole: The ferocious battle in the crater ends instantly when Bond blows up the space ship. Why? Aren't Blofeld's men still going to try to defend themselves? How do they know Bond has succeeded in his mission? They can't see the control room, let alone the television sets.
Plot hole: Towards the end of the film when Newman and the remaining stagecoach people are in the cabin at the top of the hill, Richard Boone's character sends one of his two henchman (the Anglo, not the Mexican) around to the back of the cabin to apparently surprise them from behind. Then Newman's character walks down the hill and Boone and the Mexican henchman are all killed in a shootout. Everyone comes out of the cabin, comes down the hill and the credits roll. I guess that now, almost 40 years later, that poor Anglo-henchman is still behind the cabin, waiting for them to come out.
Plot hole: In one scene, he's driving from Los Angeles to Berkeley in a hurry, and crosses the bridge again (in the wrong direction). But the most direct route from L.A. to Berkeley doesn't require you to cross the Bay Bridge in EITHER direction.
Plot hole: When Quatermass is being admonished by the senior minister for talking to the press, Breen gives his own theory to explain the presence of the spaceship: He says that it was used a propaganda weapon in 1944 and that the figures inside were made up of scraps old skin and bone, why was he unable to explain how the hull of the spaceship was heat resistant up to 3,000 degrees and harder than diamond?
Plot hole: When Mr. Bigger arrives at the hospital, he slides out of the trolley. Look carefully : he was not in the trolley.
Plot hole: When the Major and Wadislav walk up the stairs in the German mansion they are met by a pair of German officers who say something to them. Wadislav then tells the Major that he couldn't understand a word they said. What they actually said was 'Nice weather, wouldn't you agree?' Wouldn't you think that a man who speaks German well enough to convince the guards in a German HQ would understand such a simple phrase? Wadislav was chosen specifically for his ability to speak some German.
Plot hole: The neighbor girl, using a pre-arranged code, rings Audrey Hepburn's apartment twice when Richard Crenna leaves the phone booth across the street. Hepburn thinks she now knows that Crenna is mixed up with Alan Arkin's strange mix of strange friends who have come to get back the long missing heroin-filled doll. However, anybody could have been coming out of the phone booth. It strains logic that Suzy would make that deduction. (01:25:00 - 01:31:00)
Plot hole: At the beginning of the movie, Reese (and Walker) rob from a "drop" at Alcatraz. Reese uses that money to pay off "The Organization." At the end of the movie Brewster tells Walker the only place to get cash is at the drop. "The drop is the same but the location has changed." Brewster receives the money at the drop. This makes it clear the original drop was stealing from "The Organization." Why would Reese be able to pay off "The Organization" by stealing their own money from them?