There is no concept of unplugging or work-life balance. You are expected to be on at all hours of the day, evening and night. Kinda negates the salary to be honest. If you do not live to work, this place is not for you.
Perpetually understaffed, and you will have to take on other people's work often due to colleagues being swamped while still having all your work done on time (what is eating and sleeping?).
HR "department" consists of one person, so expect delays in communication.
At-will termination is a constant worry even if you are doing your best.
Boys' Club-esque office politics have been a source of frustration in the past few years.
I have watched some of the most honest and deserving colleagues get laid off just before the holidays. Your company runs on the backs of your employees - treat them with respect especially given how much they are required to sacrifice for you.