As Perez went to overtake Leclerc for P2, Carlos Sainz sneaked around the side to overtake the Red Bull.
The Mexican attempted to fight back, and pulled alongside Sainz before the two collected one another and smashed into the barrier.
Their incident prompted a Virtual Safety Car with the cars running to the chequered flag under these conditions, where Piastri took the victory.
Sainz and Perez have both been noted for the incident, in addition to a few more surprise investigations from the stewards.
Max Verstappen, Nico Hulkenberg, Esteban Ocon and Pierre Gasly all being placed under investigation by the FIA for overtaking under VSC conditions after the chequered flag.
The Dutchman was seen giving Norris and George Russell a thumbs up as he drove past them after the chequered flag was waved, with the race already concluded at this point.
“I didn’t pass under the VSC, we crossed the line, the race was finished,” Verstappen said to Sky Sports after the race.
“There’s a lot of examples where we’ve done the same thing, so I was a bit surprised.”
McLaren have overtaken Red Bull for the lead of the constructors' championship after Baku, with the British team on 476 points whilst their rivals have 456 points.