Star Wars Episode 6: Return of the Jedi - Fast Healing
When Luke is on the sandbarge holding his lightsaber in the air he gets shot on the back of his hand by a guard. This leaves a large black burn through the skin to his mechanical hand. Now when Luke grabs Leia and swings across to the next ship his hand has healed.
Anyone who watched the TV series The Six Million Dollar Man, about a man with bionic parts, would not consider this a slip up. The pain receptors in the bionic hand maybe damaged (leading Luke to feel pain) as well as lose skin but still have functional use of the hand. Kind of like when your car transmission goes out but you can still drive it in first gear.