The Would-Be Prince of Darkness - S1-E3
Plot hole: During the credits, Chloe said of the victim "coroner puts her time of death between 1 and 3am", and she does indeed ask Ty's obsessive fan / ex-gf where has she been during that timeframe. When she looks at the security tape, the timecode starts rolling at 22:18 and goes on "for 3 hours." That does not account for the time of the murder at all, she has no alibi for the second half of the suspected timeframe! Not to mention, she said she saw Ty kiss the victim. When could she possibly have seen that? It's unlikely that before 10pm Ty was already drunk and getting randy with the girl, with the house full of guests. (00:25:00)
Lucifer, Stay. Good Devil. - S1-E2
Continuity mistake: Chloe is being debriefed by her ex about the crime scene. There's a close-up of the photographer who will be the key of the case, being physically pushed away by a policeman. The scene goes on with him in the background in many shots, all on his own, snapping away as if nothing happened. (00:08:55)
Other mistake: Throughout the episode, Lucifer's car has a California license plate - but that is, just one. He is missing the one in the front. In the following episode the car does have the regular 2 plates, and when he is pulled over at the beginning (and keeps being around cops all the time), nobody raises an eyebrow at the violation of the code.
Character mistake: When trying to decipher what the letters from the dermal implants spell, Lucifer rearranges the letters and says "Hilii Fircus, it means 'children of the goat.'" However, the correct phrase was Filii Hircus, not Hilii Fircus. (00:13:27)
Lucifer, Stay. Good Devil. - S1-E2
Continuity mistake: At the beginning, the preacher is walking around with the donation mug. The first kid to put a few bucks in does it across two shots and has a very notable yellow hand-held device when he puts the money in that was not there in the first shot. (00:02:00)
Continuity mistake: During the scene in the school corridor with Lucifer sitting down and talking to Chloe's daughter, the same extras keep doing erratic back-and-forth for no reason (for instance the girl with a white jacket and pink shoulder bag) or just plain wrong (the kid with the horizontal striped maroon sweater who walks twice past Lucifer early in the convo). (00:24:50 - 00:25:50)
Lucifer, Stay. Good Devil. - S1-E2
Continuity mistake: Lucifer tosses the ninja chemist doll towards the door, and it lands on the rug in front of it. Nobody picks up the doll, but when Chloe shoves him off the premises, the doll has disappeared. (00:17:00 - 00:18:10)
Lucifer, Stay. Good Devil. - S1-E2
Continuity mistake: The quantity of blood on the door changes between shots, incoherently, when Jimmy is hurting himself, smashing his head on it. (00:42:35)
The Would-Be Prince of Darkness - S1-E3
Continuity mistake: Lucifer gets waken up after his very PG foursome by Ty. When he says "Can you just help me, please?" Lucifer does not have his right hand on the shoulder of the girl, in contrast with the earlier and following take. (00:06:15)
Continuity mistake: When Chloe turns the picture of the cufflink upside down to Dan, her grip on the photo changes between shots. In one, she has one finger behind the picture, but in the front angle, all of them are at the front. (00:33:10)
Continuity mistake: When Onyx opens the box, the way he holds the lid changes between shots. (00:19:50)
Continuity mistake: At the start, the man's hands change position around the woman during instant cuts. (00:01:40)
Continuity mistake: When Lucifer is walking towards the cowering Lindsay, she has her gun in her left hand. When the shot changes to behind Lucifer, the gun is now gone. (00:34:20)
Continuity mistake: When Lucifer hands Linda the leaflet in the carpark, the way he holds it changes between angles. In one shot he's holding the sides and in the next he's holding the top. (00:25:40)
A Priest Walks Into a Bar - S1-E9
Continuity mistake: When Malcolm asks Amenadiel if food tasted this good before he died, his hands are clenched into fists with one finger pointing at the food. When the shot changes his hands are open and just facing forward. (00:39:20)
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 ★