You want it in chronological order? I don't have the full list (there's just way too much stuff to remember off the top of my head), but here goes.
- Staged a coup of John Stockton while he was on the Jazz, causing Stockton to retire.
- Cheated on his wife with a stripper, then getting blackmailed by the prostitute + some other guy, while at the same time being a born-again pastor
- Bristled at Mike Malone being the assistant coach under him (ownership wanted him to be the Associate Head Coach, like Gentry was with Kerr, but when Jackson found out he said NO WAY
- Didn't let assistant coaches do interviews with press because he thought they were gunning for his job
- Pushed Malone out because Jackson thought Malone was gunning for his job
- Ran ISO-ball all the time
- Instilled a "us vs them" where the "them" was the entire front office. He would tell the players that the front office didn't want them to win so that Mark Jackson would look bad. C'mon that's lunacy
- Barred Jerry West and Jim Barnett (the beloved TV color guy) along with everyone else from practices so they couldn't hear the crazy shyt he said to the team
- Told the team Ezeli was rooting for them to lose so that Ezeli would look better (he was injured). This culminated in Ezeli in tears saying that there was no way he would do this, when confronted by the team
- Told the team that Harrison Barnes was possessed by a demon, which is why he regressed
- Darren Erman, the assistant responsible for the defense after Mike Malone left, was recording Mark Jackson surreptitiously to try and capture the crazy shyt like the Harrison Barnes demon thing and the Ezeli thing, but was caught and fired
- Noted homophobe, including the "I'll pray for him" when discussing Jason Collins coming out. This doesn't fly in the bay area when a lot of the team staff is gay and so is the front office, including the COO/President Rick Welts
- Didn't want to hire actual good assistants, instead, he hired yes-men like Pete Myers and Lindsay Hunter, who backstabbed Alvin Gentry in Phoenix to get the head job
- All the coaching staff were allying themselves with star players instead of the players who actually needed their help/development, so a lot players like Barnes didn't get the development time and help they needed
- He put players against each other, telling a star player "hey that bench thinks he's better than you" and then telling the bench guy "hey that star guy thinks you're shyt, go take his job"
- Didn't get along with anyone in the front office, including Jerry West, Bob Myers, and actually the rest of the employees (marketing, PR, etc)
- No preparation. He said in the Clippers series that he didn't need to prepare extra hours, when Doc Rivers was up all night devising schemes
Not to mention that he was just a really horrible coach. I'm sure I left out a lot of stuff.
Edit: I see you guys asking for a source on the Barnes Demon thing. One source is a message board post where a guy said he talked to Darren Erman in a bar, and Erman told him the story. The second (the one I personally believe) source is a Warriors reporter telling me this personally. I can't give you guys proof of this since he told it to me, so you'll have to take it w/ a grain of salt. I don't expect you guys to trust some random guy's word online, so make of it what you will. But to me that's 2 sources (one personal, which makes it more believable to me).
I forgot some more post-coaching shytty things he did:
- Saying rim protectors are obsolete, which threw shade on Bogut, and then saying Deandre Jordan was the DPOY (over Draymond) because of his rim protection
- Wanting to take credit for Kerr's success talking about caterpillars and butterflies
- Saying Curry was not the MVP, which is fair, but not what you expect someone to say when Curry went to bat to keep Jackson's job. Maybe thought Curry didn't try hard enough, which is bullshyt since Curry tried very hard and stumped for Jackson personally
- Saying Curry was ruining the game