It’s a movie both literally and figuratively about signs.

Like there’s the obvious foreshadowing like:

1. Bo leaves glasses of water around the house which plays a major part in the the climax.
2. Morgan has asthma which ends up saving his life towards the end.
3. The sheriff mentions that a lot of local dogs are acting scared “as if they smell a predator”
   
4. Merrill was a baseball player which plays a major part in the climax scene.
5. The mother’s last words were “swing away”, playing a major part in the climax scene. There’s also a scene where he mentions he chose not to become a pro baseball player because “it didn’t feel right to take a swing”
6. The alien trapped in Reddy’s pantry is the same alien in the climax scene.

But there’s more subtle ones that are usually only noticed in the second watch through:

1. When the family dog starts acting weird, Bo says he should be taken to the vet, but Graham says to take him to the local doctor. Morgan says something along the lines of “but he won’t even know what to do”. Graham wont take the dog to the local vet because he’s the man that killed his wife. You only learn that Reddy is the vet in a quick shot of his mailbox, which lists his profession on the side.
2. Crickets stop when the aliens are nearby even if they don’t show up in the scene.
3. There’s empty places on the walls in the farmhouse where crosses used to be, taken down after Graham lost his faith.
4. Towards the end of the basement scene, it’s revealed that the aliens have quickly retreated, leaving their wounded behind, for example the pantry alien at Reddy’s house that Graham had cut the fingers off of when it grabbed for him under the door.
   
5. It’s also hinted at that Bo has prophetic dreams, and there’s a one off scene where she says she doesn’t want Morgan to die while he’s looking through a telescope, and he is the only one of the family that actually does become close to dying after having an asthma attack and then being sprayed with poison by the alien.
   

Not only that but there’s so many well shot scenes and good quotes and in the cornfield jumpscare scene thank god they didn’t use a LOUDASS noise like modern scary movies do, but rather have a quieter music cue but it’s still scary ugh THANK YOU. This also happens in the pantry scene where the alien shoves his hand under the door, as well as the basement scene when the alien is sneaking down the coal chute. The music in general is so good for the movie.

Morgan in the first scene thinks God made the crop circle and it’s shown throughout the movie that Morgan is a ‘believer’ from the beginning and has fights about it throughout the film with Graham who is no longer a believer. This mirrors the internal struggle with Graham and him losing his faith, both with god and with the events of the movie. There’s also a scene with Graham and Merrill on the couch where they’re talking about if there’s such a thing as fate. He reveals to Merrill that the wife’s last words were “swing away” which makes Graham think that, as she was dying, her mind was just replaying random memories of one of Merrill’s baseball games, leading Graham to begin losing faith and his belief in fate, however it’s later revealed that it was the exact opposite, she was giving him a sign.

Shyamalan, the man who wrote/produced/directed the movie, also plays the character who killed the wife, setting things in motion as the movie plays out. I usually don’t like it when directors play characters but least it’s fitting here. 

The camcorder footage they play on the news is like. One of the scariest reveals ever idk maybe it’s just because I was young when I first saw it but it’s just really good. There’s also a bit during this scene where a bird is shown flying into an invisible wall, leading people to believe the ships use some sort of cloaking device in the daytime. In a deleted scene, the family drives by a dead bird, hinting that there’s a ship, unseen, nearby.

They don’t show the alien in full lighting until the camcorder scene which makes it even more scary to see. And beforehand they only show glimpses of it which is like, rule one in horror storytelling that so many modern scary movies break. DON’T show the monster, because the suspense of knowing it’s out there but not knowing how horrible it is, is a much more powerful tool in creeping people out. Also the CGI in this movie sucks ass so it worked in their favor.

The scene with the baby monitor when they’re on the car is SO GOOD. Plus the signal only becomes clear when they all hold hands which I wouldn’t count as foreshadowing but important nonetheless. Later in the movie there’s a bit of an argument at the dinner table BUT then they have like a group hug and only when they’re all touching again does the baby monitor start picking up the signal again.

The way they reveal the alien in the climax scene by using the reflection in the TV monitor and then the music swell they play when they’re going through all the flashbacks as everything finally comes together. BEAUTIFUL.

MOST IMPORTANTLY: The tinfoil hats are adorable and hilarious.