Victory had been imperative for an Arsenal side that had won only two league games since January but the abject display with Andros Townsend, Yohan Cabaye and Luka Milivojevic all scoring for Palace only heaped more pressure on manager Arsene Wenger.
Arsenal's players then faced a barrage of abuse from their own supporters as they boarded the team bus to depart Selhurst Park, with the likes of Theo Walcott, Granit Xhaka and Olivier Giroud jeered loudly.
Bellerin sought to meet the Arsenal faithful at full-time following the loss but was instead booed, leading to the full-back turning and walking away before being consoled by Alex Oxlade-Chamberlain.
Fans also turned on the players during the game, chanting: "You're not fit to wear the shirt" as they offered little resistance against Palace.
Wenger is regarded as Arsenal's most successive manager ever, but his reputation has become tarnished in recent seasons after his failure to win major silverware.
The sixth-placed Gunners needed three points to keep them in the hunt for Champions League qualification, but the defeat leaves them seven points off the pace.
And Flamini concedes he did not enjoy seeing his former club suffer, adding that fans have a right to be angry because they expect to see more from the team.
"I think it will be very hard certainly", he said.
"Like I said before, this isn't Arsenal at this moment time. Tonight, the worry is not me, it's the fact we lost a big game".
"I just think, from top to bottom this club is not right", he said.
"In the second half they came out strong and scored again".
The Spaniard went to applaud the travelling support at full-time, but was noticeably booed before he trudged back to the dressing room.
Carragher singled out Arsenal stars Alexis Sanchez and Mesut Ozil for the most criticism, saying they have been "playing to get away".
"Honestly, I am disappointed tonight".
Palace winger Zaha is said to be among his targets following an outstanding season for Sam Allardyce's men, and he will battle with Tottenham for the player's signature.
"All we can do is apologise for that performance".