Alexandre Lacazette's fortuitous finish in stoppage time sealed a 4-0 win at the Emirates Stadium but, more notably, was the striker's first goal in 10 games.
Lacazette had lost his place in Mikel Arteta's starting XI due to a goal drought stretching back to December 12, but scored in the dying seconds.
The Frenchman was congratulated in style by his team-mates, with Lacazette telling reporters after the game: "I am really, really happy because I waited for this moment for a long time.
"As well, I am touched because of the way all my team-mates reacted when I scored that goal. It means a lot to me and a lot for the spirit we have in the team. This is good."
But Keane was not as impressed, claiming the Arsenal players' celebrations were "way over the top" considering the occasion and their opponents.
"I thought they were ten points clear at the top with those celebrations," he said on Sky Sports.
"No, no, forget Arsenal. Way over the top celebrations, beating Newcastle 4-0. Ridiculous."