Early in the film, Dave's truck license plate says MATT 725, seen out the garage door during the hurricane. Matthew 7:25 in the Bible reads "The rain came down, the streams rose, and the winds blew and beat against that house; yet it did not fall, because it had its foundation on the rock." (NIV)
Out of all the movies that were released in 2019, Quentin Tarantino has selected this one as his favorite.
It was Kaya Scodelario's idea for her character to be barefoot for most of the movie. She fought to have her character barefoot because she knew, as a woman, if you step in poop or mud in flip flops, your instinct is to take them off.
The last name of the main protagonists is 'Keller', which is the German word for 'basement'. The largest part of the film takes place in a basement. However, it remains arguable whether this was intended by the film makers.