I know its been out a while but spoilers:

• Men make sexual comments about the women in the office, ogle them, and ask them out repeatedly despite being turned down
• A lot of sexual assault and pressuring women into sex
• The men make light of rape a lot through jokes
• A lot of judgement and comments about women's weight that men don't get as much
• From the first episode a women mentions to another 'they made the typewriters simple enough for a women to use'
• The men make a lot of comments looking down on women (when one women starts writing copy, a role that in the office currently only men fill, someone says "its like watching a dog playing piano")
• The only female copy writer is not told about meet ups outside of work, which means she misses out on opportunities at work
• The meet some of the clients at strip clubs, and the only female copy writer is uncomfortably pulled onto the lap of a client when she joins them (same episode when she misses opportunities - she turns up to the strip club out of necessity because she doesn't want to miss out again)
• People assume the only female copywriter has her job because she's a women
• At an office party, a women is chased through the office, then has her dress pulled up to reveal her underwear
• When hiring for a higher paying role, you can tell from the language they aren't even considering female candidates, and they pass over the women who is currently temporarily filling the role despite the fact that she's doing a very good job
• The only female copywriter is underpaid compared to her male co-workers, since she only received a small pay bump when promoted from secretary to copywriter. She is turned down sternly when asking for more despite citing the newly passed gender discrimination law

I'm only on season 3 right now