(Spoilers) Needed a script overhaul...
I didn't see the twist coming and I thought it was clever... until I started thinking a little more deeply about it.
There are all sorts of logical and logistical problems with the twist that many others on this board have already pointed out. However, with more work on the script, I thought these could have been overcome.
The biggest issue is: How could they NOT know that they were androids? Have they never been to doctors, had accidents, etc? Did they not wonder why they didn't age... why their kids never grew up? What is the purpose of this entire facade? (Some of these androids are in the know and work to maintain the illusion... but why?)
A script overhaul could have suggested...
We see that past fake-memories could be implanted in them. Why not future ones as well, i.e. memories of doctor visits, accidents, etc that are 'activated' at certain times? At periodic intervals, child robots are de-commissioned and replaced by slightly older looking versions and then memories of all concerned are adjusted accordingly.
A script overhaul could also have explained the purpose of maintaining the illusion which is never really addressed.
This all introduces its own set of problems, I realize. This was just a top-of-my-head ideas... The bigger point is that there was a real opportunity to produce a good sci-fi that explores some big ideas but it was squandered with a subpar script.