Manager David Moyes was angry with the catalogue of errors which gifted Brighton a 3-3 draw and left West Ham in the drop zone.
The Hammers' nemesis Glenn Murray scored a controversial late equaliser, his seventh career goal against West Ham, as Brighton snatched a point.
The ball appeared to hit Murray's arm before he fired home but a VAR check decided otherwise, to disbelief in the stands when the replay was shown.
But Moyes said: "I've looked at the goal and I'm more disappointed at the defending than VAR.
"We should have cleared it. It was nearly as bad as their second goal. It was nearly as bad, but not quite."
West Ham were 2-0 up through first-half goals from Issa Diop and Robert Snodgrass, but gifted Brighton a way back in when Lukasz Fabianski punched a corner onto the shoulder of defender Angelo Ogbonna and conceded an own goal.
Snodgrass restored the two-goal cushion but then a defensive horror show from Diop and Fabianski allowed Pascal Gross to nip in and score.
Murray's moment arrived in the 79th minute and a lengthy VAR review eventually showed the ball had not touched his hand before he swept it in at the far post.
Brighton were only denied a late winner by Fabianski's save from Solly March.
"In the main we were very good but for a couple of really silly mistakes," added Moyes.
"We offered a threat, as did they. The performance was good but it's tarnished by a couple of mistakes.
"We gave them a leg-up for 3-1 with the own goal, and we gave them a massive leg-up with 20 minutes to go.
"I'm angry and the players know I'm disappointed. Their effort was huge. I just feel playing Liverpool on Wednesday night and fatigue played a part in the second half."
A draw meant West Ham slipped into the relegation zone and with trips to Manchester City and Liverpool next up, it might be a while before they climb back out.
Brighton are two points better off and boss Graham Potter said: "I'm very proud of the players, proud of their reaction to being down in the game. We had to suffer a bit.
"Mistakes don't just happen on their own. Something has to force them to happen. We pushed and pushed.
"In the second half the game was played in the opposition half and their keeper has made more saves than ours."
Potter was on the touchline at the London Stadium despite the death of his father just two days earlier.
He added: "It's been tough. Thankfully I've had a lot of support from the club. My father was proud of me and proud of what I did, so it was my job to do it the best I can."
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