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)

Starring: Lauren German, Kevin Alejandro, Tom Ellis, Lesley-Ann Brandt
Genres: Fantasy
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)
What Would Lucifer Do? - S3-E4
Other mistake: When Lucifer grabs Amenidiel's phone and is supposedly typing on it, he's holding it upside down. (00:06:25)
Answer: It's Lucifer's blood from when his wings got hit by the bullets. As Lucifer spreads his wings, they're white, and before he wraps them around Chloe, you see a bullet hit his wing above his right shoulder, and the spot turns red. After that, he continues to get shot in the wings before fleeing.
Bishop73
Agreed. His wings take damage and "bleed" similar to how he bleeds when Decker is around.
Ssiscool ★
If they were normal bird's wings, the lower part where there are just feathers should neither bleed like that nor be able to stop bullets, but they are angel's wings, so they behave differently.