An early forerunner of the geeks who traveled into movies in my previous post, in Die Einsteiger, is Buster Keaton, who does a similar trip in his 1924 film Sherlock Jr.
While the 1980s were a period in which the dramatic device of choice was a blinking and beeping machine, this earlier film from the 1920s uses a more traditional approach: the protagonist is just dreaming that he enters the movie world. Here's how it looks (watch until approx. 22:30):
Keaton plays the operator of a movie projector at a film theatre; he falls asleep while a picture runs and dreams that the characters in the film transform into people from his own life. He then walks up (still dreaming) to the screen and steps right into the scene that is being shown. In other words, he enters the world of the movie and starts interacting with its characters.
This is a very early example of how such a situation is staged. It's a comparatively prolonged and elaborate sequence, as the film tries to get the idea across that the main character is now entering a movie. But it includes all the elements I have discussed in my previous analysis.
Let's begin with setup and recognition. Before the actual passage happens, we are introduced to the world of the movie into which Buster is about to step. It is set in a villa and there's its owner, his daughter, and a young man (presumably her suitor). Each of the characters is briefly shown and then turns around and transforms into a person from the projectionist's world, noticed by the dreaming Buster. This is what I've called setup: elements of the destination world are introduced to us (the audience), as part of the departure sequence. Later on, in the arrival sequence, these elements are then used to show us that the traveler really has arrived there. In the case of Sherlock Jr., the plot of the movie into which the protagonist steps resumes in earnest (after a bit of slapstick comedy) with the daughter of the house and her suitor on the stage. This is supported by one or two cinematic tricks: one of them is a circle-open effect (as if we're opening our eyes to the scene); another is that the camera now zooms in so that the stage of the nested movie fills the entire frame. So far, we have watched the movie-within-the-movie on a cinema screen, with bits of the orchestra and audience visible. Now it has become exclusive: there is no intruding outside world any more, we're fully immersed in the nested picture's world. We have now moved into the recognition part: the elements that were introduced earlier, during the setup, are repeated so that we know we have arrived. (In this case, it's only we, the audience, who have arrived. Buster will follow, though he is already mentioned in absentia as "the world's greatest detective".) We witness a bit of interaction between the daughter of the house and the suitor, and then the villa's owner discovering the theft of the pearls. With the telephone call for Sherlock Jr. and Buster's subsequent appearance (not in this extract), the arrival scene ends.
Where exactly would we pinpoint the departure and arrival sequences? I'd say that the departure sequence spans the time from Buster falling asleep to the end of the slapstick intermezzo (where he is thrown into one location after the next). When he finally fades out of the picture, in the setting with the empty park bench (quite conceivably the front garden of the villa), he has entirely vanished from the surrounding setting in the movie theatre, has lost his presence in the outer movie's world, so to speak. He really has departed. The arrival sequence, on the other hand, somewhat interleaves with the departure sequence. In a sense, the arrival begins when he first steps into the frame of the inner movie. He is promptly knocked out of it again, and then needs another attempt to step in until it holds. When the departure sequence has ended, and the inner movie resumes its plot, this is made clear by the cinematic tricks I've mentioned above. A little later on (not in this extract any more), Buster appears in the role of Sherlock Jr. — at this point at the latest I think the arrival sequence is completed.
Finally, note that again there is a shifted transfer: when Buster has already entered the world of the inner movie, we (the audience) are still located with a perspective that includes both the outer and the inner world, the origin and destination locations. Only after Buster has completed the passage and is firmly located at the destination, the audience's perspective also changes to focus exclusively on the inner movie's world.