Continuity mistake: At the start when Trixie comes running in to give Lucifer a hug, Lucifer has got a jar in his hand. As the shot changes to him actually being hugged, the jar simply vanishes from his hand. (00:03:05)
Visible crew/equipment: When Chloe shuts the door on Dan, a stage light is reflected in the glass of the door. (00:04:10)
Continuity mistake: The squiggle that Lucifer draws over "Become God" on his checklist changes between shots.
They're Back, Aren't They? - S3-E1
Audio problem: When the criminal in the armoured truck tells Lucifer to get out, from the angle over the criminal's shoulder, his mouth isn't moving. (00:02:30)
Continuity mistake: When Lucifer hands Decker the blue cup at the party, the way she holds it changes between shots.
Expire Erect - S4-E5
Continuity mistake: Near the end, as Dan says "this is all on me", in a shot from behind her Maze is spinning her knife then stops, gripping it pointing downwards in her fist. Cut to a new angle and her hand is instantly turned over, with the knife sticking out sideways.
What Would Lucifer Do? - S3-E4
Continuity mistake: Pierce starts to put his phone away, then the shot cuts to him still on it. He then actually puts it away and then again it is in his hands, and he puts it away again. (00:31:28)
Factual error: The record producer is holding a pistol model 1911 or 1911A1 which is a .45 caliber handgun with a standard magazine capacity of 7 +1 rounds, the +1 being loaded in the chamber, however newer magazines hold 8 +1. Therefore, this handgun can hold a maximum of 9 rounds, however the producer fires 10 shots before Lucifer grabs him. Newer 1911 style pistols are now produced in 9mm which have a greater capacity but the pistol held by the producer was a standard 45 ACP judging by the metal and finish. (00:37:38 - 00:39:18)
Deliberate mistake: Lee's old crew of three are shooting various caliber handguns at Chloe and Lee's sister. Chloe took cover behind a kitchen island. Kitchen islands are made of thin wood, the only piping in them is plastic and some brass/copper. All of those handgun calibers would have penetrated the kitchen island. (00:45:45 - 00:47:00)
Quintessential Deckerstar - S3-E23
Audio problem: Chloe enters the scene with her handgun drawn. She carries a Glock 19. Glocks are striker fired and have no exterior safeties to click or lower which would produce a sound, however when she draws and points her gun a click can be heard. (00:34:25)
Other mistake: When Maze is knocked down by Lucifer the second time, the footage used of her on the ground is the same footage from when she got knocked down the first time.
Other mistake: When Julian is in custody, being interviewed by Chloe, a lawyer comes in and says a judge has released Julian on his own recognizance. Then Chloe asks what happened to the $2M bail and the lawyer says it's already been paid in full. It's one or the other, if he was released on his own recognizance, no bail would have to be paid. If the bail has been paid, he would be released and no need for a judge's order. Not to mention the fact that all of this takes place the same day he's brought to the station and hasn't had a bail hearing. He didn't even seem to have been processed, he was just being questioned.
Lucifer, Stay. Good Devil. - S1-E2
Other mistake: We are shown several times the first person perspective of a paparazzi camera, with the HUD. From a diegetic point of view though, it is used in a way that lacks coherence. For instance, in the red carpet scene the photo count goes down by one every time the shutter clicks, while in the car scene it does not go down at all. And it really could not have been Josh's camera in the red carpet scene, because it photographed Chloe once he already escaped and from behind.
Lucifer, Stay. Good Devil. - S1-E2
Continuity mistake: In the interrogation room with Nick, more than once (for instance when Lucifer says at the beginning "I don't want to know about the case") when Jeremy Davies lifts his open hands and holds them up, they are held up at a different height between one shot and the reverse. (00:18:50)
Lucifer, Stay. Good Devil. - S1-E2
Continuity mistake: The fake preacher runs away leaving all the money behind: in the overhead shot Lucifer says "I'm here till, well, the end of times actually" turning around past a guy (big hair, big sideburns, black and blue shirt) that he already passed in the shot before as he thanked the crowd. (00:03:20)
Continuity mistake: Lucifer walks down the stairs into 2 Vile's mansion; first person he comes across is carrying a glass, wearing a black T-shirt and grey undershirt sticking out. The guy is walking towards Lucifer as if he were going to use the stairs Lucifer is descending, but just vanishes in the following shot, only to reappear at the next cut, taking the stairs as it seemed bound to happen all along. (00:16:15)
Continuity mistake: When Lucifer talks to the killer in agony in the car wreck, blood streaks change on his face between shots (in particular, he has blood coming from the corner of his moith in the last shot, from the side, but he had none a moment before, in close-ups). (00:09:40)
Lucifer, Stay. Good Devil. - S1-E2
Continuity mistake: Immediately after the close-up on the poster of Demon Town with Penelope Decker, Lucifer holds the trophy. From behind it's evident that Chloe's healthy arm is down her side, but in the reverse shot she has her arms crossed. (00:17:30)
The Would-Be Prince of Darkness - S1-E3
Continuity mistake: Chloe takes the phone in Lucifer's hand as he is watching the registration. Depending on the angle Chloe has her right hand on the phone itself or off it, signaling Lucifer to stay put. (00:13:15)
Answer: Boo Normal and Once Upon a Time were going to be part of season 4, then the show got cancelled (before being picked up elsewhere). As such they were added on to the end of season three as "bonus" episodes, hence the continuity being off. But not really a mistake, just a quirk of broadcasting. Boo Normal was originally going to be between the episodes "High School Poppycock" and "Infernal Guinea Pig" in season 3 before being slated for season 4, presumably because aside from the point you've raised, it was fairly flexible, continuity-wise.
Jon Sandys ★