This episode could have been more interestingly created if more details were given at the END of act 3. I completely agree with Philip M. The first two acts could have been shorn-up in 5 minutes leaving the rest of the episode to strengthen the plot. What you were left with is a big set up to one of the worst endings in Mystery Theater history. Anna was provocative and had some scrupals--Victoria Dann (the episode's writer) should have played up on that more effectively. In the end, "The Unregistered Aliens" was just a so-so listen worthy of just 3 stars.