3 things that bugged me... (Spoiler Alert)
1. Super Market opening scene... So in this world, staying quiet is vital, yet they trust their toddler to run around an abandoned super market, which can be quite messy, chaotic with objects everywhere. You trust your little toddler isn't going to make an accident? When the Dad appears, he even instructs the toddler to go get his mother. And when they leave, the parents walk ahead of the kids! With the toddler being the very last in line! SMH!! So can we really be shocked when this boy is the first victim? They are so careless! BTW, toddler, or 4-6 yrs old, it doesn't matter, the point is he was the youngest.
2. Getting pregnant in this world, really? Okay, maybe this one is explainable. Perhaps, she got pregnant before the "whole thing" happened. Whole thing as in virus outbreak, alien invasion, etc. We don't know what happened.
3. The Nail... although nobody else stepped on it. The nail was never removed, and there wasn't any scene to let us know the mom warned them about it. Even in the end when the three of them went down the same stairs, the camera focused on the nail. Obviously to make the audience nervous and wonder if any of the kids will step on it. You could argue that the family knew about it, and it didn't have to be explained on camera, but due to the continuity of the movie, I didn't see any opportunity for them to have this conversation off screen. If we are to assume that they did have a talk about how she injured her foot, and are aware of the protruding nail, and if the nail is no longer a problem then why zoom in or focus on it? Obviously to scare the audience. But like I said, it's illogical because it would be common sense for this mother to warn her kids. It wouldn't take much to do it also. Since she went down the stairs first, she could point to the nail, do some gesture, etc. But nope, nothing, no warning for her kids. Neither stepped on it, so it was their lucky day, no thanks to the mom. LOL!
Having said that... I enjoyed the movie, it was very tense!