The first time John Smith puts on his holster and pistols, the grip frames are pointing behind him. This would make it very difficult for him to pull the weapons in a timely manner when needed. However, when the time comes minutes later for him to pull the weapons, the grips are facing in the appropriate position for a quick draw and shoot.
At the beginning of the film, after ordering a whiskey, John Smith (Bruce Willis) is eating from a bowl. The bowl was not visible before hand on the bar, and Joe Monday (William Sanderson) did not fill a bowl from the stove behind the bar.
(From 1:13:30 to 1:13:40) In the opening scenes of "Ira, You Are The Man", the sprinkler system used to make it rain has two of the sprinkler heads and piping clearly visible at the top of the screen where the lightning is flashing.
When the .45 automatic pistols were shown, they were the M1911A1 model because they had arched mainspring housings but with double diamond grips. M1911 pistols had flat housings and diamond grips. M1911A1 have flat grips.
When Jacko slams the double doors shut on the room where the captured and beaten John Smith is being held the locks are visible on the John Smith side of the doors. Later the locks are shown, properly, on the opposite side.