Is This Really How It's Going To End?! - S5-E15
Continuity mistake: When Dan hands Ella the phone number, he's holding it by pinching it on the bottom. In the next shot, he's holding it on the side.
A Chance At a Happy Ending - S5-E16
Continuity mistake: A guy with a face tattoo is in the opening scene, then the tattoo isn't there when the guard gets up.





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.