Audio problem: When Max is on the front of the people eater's truck, the gunman shoots at Max, then briefly stops. When he starts shooting again, the sound effects of the shooting are too early, as there are no flashes from the gun.
Continuity mistake: During the final chase sequence when Max is on the front of the Doof Wagon, the wires hanging in front of the speakers change from a single black cable to many twisted multicolored wires between many of the shots. (01:42:00)
Continuity mistake: When Immortan Joe's body is thrown from the car it lies parallel with it, but when the crowd rush in it's now at an angle, with his feet pointing away from the side of the car.
Continuity mistake: When Max jumps from the War Rig to the front of the People Eater's limousine the metal accent on the far left of the bumper goes from angled to straight. (01:37:00)
Continuity mistake: Towards the end of the film, when Max is fighting the guitar playing doof warrior on the doof wagon and the guy loses his guitar, it then cuts to a front shot of the action on the vehicles in front of the 'band wagon' but in the background the guitar guy is still playing, it then cuts back to Max fighting him without his guitar.
Answer: The canyon pass was cleared by Immorten Joe's men - the archway was never blown up. it was the canyon side in front of the arch that was destroyed.