A counterpoint to something I keep seeing mentioned on here

"Wouldn't the fact that the real grandparents hadn't shown up to the hospital, and that there are also two missing patients, give off red flags to everyone to give a hard investigation to the grandparent's house?"

Let's establish the already known fact between both sides here, that a few people did actually stop by, but I think many people on this forum believe that additional authorities would investigate.

Here's the thing... you had the actual *grandchildren* there saying that everything is fine!
There's absolutely no reason those showing up at the door would think, "Oh... these kids are saying everything is fine... but maybe they don't know what their actual grandparents look like!"

No one is going to actually consider that last statement to be a possibility, because... now, I'm throwing this number out there, but I'm sure it's close, but... around 99% of 15 year olds are going to be able to successfully identify their still living grandparents!
That would be more than enough verification for most people stopping by to check on them.

I think most people judge the actions of characters in a film as if they should be self-aware of the plot and type of movie they are in.