“I just wanted it to look like a dream.” - Buster Keaton on Sherlock Jr.
Slavoj Zizek made a great point of how the human mind is the most complex cinema projector. We "see" things on the "back" of our head, which are then projected towards our consciousness. This idea was rarely seen with such efficiency as it was in this movie.
Upon realizing the movie in front of him has changed, the "ghost" of the sleeping projector realizes he's in for something different. Which brings us to my fave shot:
He points at the screen trying to call out his "owner's" attention but fails to do so, in the process reminding us of how the deepest secrets of the mind (the ones we often turn into traumas) are usually there and are usually pointing at us to see them and fix them. This can also remind us of more spiritual ideas and you have got to love how Keaton goes even more meta and sets a frame within a frame, within the larger frame of our mind which determines how we are decoding what we see.