Deliberate mistake: After Roy and Johnny rescue the man trapped under his house, when the ambulance reaches Rampart, in the shot from inside the ambulance when Roy follows the stretcher out, he stops at the receiving doors and waits for John, who just arrived in the squad, and in this semi-closeup, it's odd and very apparent that it's not actually Randolph Mantooth, it's his double meeting Roy at the door.
Deliberate mistake: During the rescue of the car at the top of the draw bridge, The Boat approaches and radios in to say that they have a diver standing by. Then after Johnny shouts, "Are you all right?" the rescue boat is shown again, but this time it's a flipped shot - note that everything is reversed from the prior shot.
Deliberate mistake: When O'Brien shows up at the nurses' station for Dixie's answer, after she declines the offer Dixie walks off to a patient who's brought in by the police, and the last closeup that's shown of O'Brien is flipped - note his hair is parted the opposite way and the background is backwards.
Deliberate mistake: At the market, after the tiger knocks over the pyramid of Hi-C cans, which were set up blocking the aisle just for that purpose, the officer tells Les, "Down that aisle," and the next shot of the aisle is a flipped shot - note the backwards words on the upside-down boxes. Two shots later that same aisle is shown properly, not flipped.