When Hector fires his pistol on the pier it makes a booming sound even though it is fitted with a silencer.
When Charlotte falls from the pier, the scene takes place in broad daylight- but when she is taken away by EMS, it is quite dark: an unrealistically long time for an emergency situation at a city beach.
This is (contrary to most films and TV shows) factually correct. A silencer reduces the muzzle speed, making the bullet subsonic, which means the sonic boom for breaking the speed of sound doesn't happen. Firing the bullet itself (the explosive charge propelling the bullet) does still give a sound.
When Charlotte throws Lucifer and Amenadiel into the piano, Lucifer steps on the keys as he gets back up. This triggers the sound of the keys' pitches being played, but there's no way this can happen due to the dismantling of the piano's components.