There are a lot of tropes in writing and a great many overly repetitive easy outs in television. How many times have you seen the following :
They look just like us :
Aliens, demons whatever but you can't tell them from anyone else because they look just like everybody else. It's an easy answer requiring less make up, less thought and well just some decent acting ability. Now on the flipside this plays directly into typical paranoia. They are all out to get me and the people I know are not the ones I can trust or I can't trust anyone because they could be one of THEM. So is it better or not than the nose implants of ST:NG?
I can't remember :
Your character loses their memories. This is usually tied in with the revelation of something important that could a game changer for everyone and then suddenly blow to the head, coma, mysterious disease, whatever equals problem solved. Of course now you have a quest to recover the memories or better yet the amnesiac wanders off and now you have to find them. Amnesia is a real condition, but it's not common- in this case it's just convenient.
Solution Amnesia :
Last week the entire show pivoted on one point: the weapon, the knowledge, the one bit that makes everything work and solves the whole issue. Now nobody remembers anything about it. Here's the solution to the problem of the day but because it's already been used it never comes back into the light again. The easiest way around this is to make sure that it's destroyed, a one use device or requires such a sacrifice to use that it's unthinkable. But there are a great many cases where the answer is just conveniently forgotten.
The body swap :
Something or some process swaps the minds or spirits of the characters around. TV shows just seem to feel the need to have this happen at some point. You can just imagine the creative team's one lone voice, "Hey what about ... you know this show did it too...". Which then brings around the next point, let's keep the shifting going because once is not enough. How about another round of body swaps? There also have to be gender swaps as well or you're just being lazy and they have to involve love interests. You have to give Futurama credit though, because they had a chart of how many swaps it would take to get everyone back. (Futurama, Farscape, Stargate for starters)
More later ...
- Overdone - Somebody Cooked These TV Ideas Until They Were Charred