Other mistake: Athena Carter (Sgt. Grant in her younger years) takes Officer McCluskey to the armored truck. She has her finger not on the trigger, but still fires off a shot (without recoil). Muzzle flash is a single frame. (00:21:14)
9-1-1 (2018)
1 other mistake in season 9 - chronological order
Starring: Angela Bassett, Peter Krause, Aisha Hinds, Oliver Stark
Revealing mistake: The captain's arm that was removed can be seen wrapped in a green screen editing sleeve when he is in the hospital. (00:39:55)