Wall Street (1987) - 3 major mistakes

Continuity: The opening shot (of the New York Stock Exchange's trading floor) has the subtitle "1985," which might lead one to expect that at least the action in the first few scenes takes place in the year 1985. However, when Charlie Sheen is talking to his Nimrod broker buddy the Nimrod jokes that the day the Challenger exploded, Gekko was on the phone "selling NASA stock short." The Challenger exploded in January, 1986, not 1985. [An explanation for this: Wall Street, as conceived and filmed, was supposed to be set in 1987. However, near the end of 1986, The Ivan Boaesky insider-trading scandal hit, many rules were changed, and acknowledging those events would have undone much of the plotting of the movie.  So the movie was shifted back in time to 1985 (before the scandals, and also before the Challenger disaster), thus creating this major goof].

Continuity: When Gecko is talking to the board of Blue Star Airlines in Bud's apartment, Michael Douglas is wearing a suit, but white sneakers can be seen on his feet. In the next shot, he is wearing dress shoes.

Visible crew/equipment: When Gecko is talking to the Airline board in the apartment, in the shot when he walks in front of the window, a boom mike is seen in its reflection.