The Brazilian forward was subject to two yellow cards in the same passage of play, resulting in a red.
Moments later, he barges over Chiquinho who is advancing toward the Arsenal goal.
With two bookable offences within seconds of each other, Oliver was well within the laws of the game when he decided to send the player on his way.
“I’ve never seen that. I’ve been 18 years in this country and I’ve never seen something like it,” Arteta told BBC Sport.
“I’m not happy with the decisions we have had this season, but that is a discussion that I will have with the officials,” he added in his post-match press conference.
“I need an explanation with what happened today. Those discussions will happen soon.”
Arsenal were ultimately able to hold on to their lead, with Gabriel’s goal proving the difference in the end.
The Gunners now move up into fifth, with two games in hand on fourth placed West Ham.