When you're watching an old movie and it makes references to an even earlier time. Future viewers may feel the same way about some of our movies.
Bob and Alice watch Who Framed Roger Rabbit;
Alice: This movie was made in the 80s but it has the look of the 40s.
Bob: That's metanostalgia. In the 80s people could still remember the 40s so they felt nostalgic for it.