Creative geography
Creative geography, or artificial landscape, is a film making technique invented by the early Russian filmmaker Lev Kuleshov sometime around the 1920s. It is a subset of montage, in which multiple segments shot at various locations and/or times are edited together such that they appear to all occur in a continuous place at a continuous time. Creative geography is used constantly in film and television, for instance when a character walks through the front door of a house shown from the outside, to emerge into a sound stage of the house's interior.
A notable and innovative example of creative geography is the TARDIS time machine on Doctor Who, which looks like a police call box on the outside but is much larger on the inside. The viewer knows that the actors are stepping into a prop and then filming at a sound stage that represents the interior, but, via creative geography and suspension of disbelief, the transition is made seamless.
An extreme example of creative geography occurred in the film Just a Gigolo in a dialogue scene featuring the characters played by David Bowie and Marlene Dietrich. Bowie and Dietrich actually filmed their respective parts separately, in two different rooms months apart: editing and shot-matching were employed in an attempt to convince the audience that these two people were in the same room at the same time. At one point, Dietrich's character gives a memento to Bowie's character: to achieve this, she handed the prop to an "extra actor", who then walked out of frame. In a separate shot, a different "extra actor" (playing the same person) walked into frame and gave the prop to Bowie.