Visible crew/equipment: When Chloe shuts the door on Dan, a stage light is reflected in the glass of the door. (00:04:10)
Sweet Kicks - S1-E5
Visible crew/equipment: When sitting down in The Paddock Bar, the man next to Lucifer is wearing glasses that reflect a light screen. (00:12:30)
Favorite Son - S1-E6
Visible crew/equipment: When Linda and Lucifer are having a discussion at the end, a light screen is reflected in Linda's glasses. (00:39:10)
Visible crew/equipment: After the brief discussion in the hallway outside Linda's office, as Lucifer walks off a green screen is reflected in her glasses. (00:11:50)
Visible crew/equipment: When Lucifer jokingly says to Ricky that there's "nowhere to go but up", part of the crew/equipment is reflected in Ricky's glasses. (00:15:00)
A Priest Walks Into a Bar - S1-E9
Visible crew/equipment: When Linda is talking to Lucifer a white screen is reflected in her glasses. This can't be the window as the window is behind her. (00:03:30)
Everything's Coming Up Lucifer - S2-E1
Visible crew/equipment: When Lucifer and Chloe are walking across the set at the start, the camera rig is reflected in the car's paintwork. (00:05:20)
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 ★