In season 4 they refer to Bosch's mother having died in 1978. In the previous seasons he was investigating her murder in 1979. He mentions to the hotel owner that the murder occurred in 1979 in season 2. In season 4 he shows Maddie her unmarked grave with the year 1978 and the killer and Bosch later say 1978 again. The times got messed up.
As the killer takes the murder weapon from the wall in the tunnel, Bosch confronts him and the killer drops his phone. After the scene changes to Bosch and back to the killer, the killer has the phone in his hand. After another change back and forth, the phone is not in his hand.