At the end, Lucifer says, "Oh, God." This is one of only two times he says "God" instead of "Dad".
This is the first of three times in which Lucifer appears in a T-shirt. The second is in My Little Monkey (2016), worn under a loose coat while imitating Dan. The third is Boo Normal (2018), worn under his suit jacket and over both dress shirt and waistcoat, while making fun of Dan.
There is at least one appearance of something "Christmas-y" in the series per season. Here it is an out-of-season Christmas tree decorated with lights and baubles in a suspect's apartment.
Maze tells Linda she made a friend - "an eight-year old who wandered into the bar." While congratulating her progress, Linda suggests that Maze's next friend ought to be of legal drinking age (and Maze agrees). The next person Maze refers to as a friend will be Dr Linda herself, in season 2's Sin-Eater (2016) - as the two share drinks at Lux.
The title is said by each of the suspects.