Interesting thread. Its covers questions that come up on sequels in general. The recent expectation that sequels are expected to refer to events of a previous movie is very odd to me. It used to never happen. Generally sequels were just another adventure without the need to refer to earlier ones. There would be the general status quo which was in place at the beginning of a new movie. Which was necessary to attract audiences who missed the last movie. It was very much like tv series of the time. The exceptions, which use to be rare, where film series which told a continuing story in each installment. Of course now that is the norm.
I remember how Bryan Singer using the term "vague continuity" was such a big deal for Superman Returns. Some people hated the very idea, separate from their opinion of the actual film. Yet really all films and tv series use to have vague continuity. There are advantages of things being more clearly planned and connected. But I miss the old days. It allowed you to use your imagination to figure out how to fit pieces together which were not really cut well. It was fun.