So… after careful evaluation I’m pretty positive Elio puts Oliver’s necklace in his mouth during the midnight love scene. Oliver’s necklace falls off as he’s getting up after Elio had tugged at his neck whilst laying down.
After this… and then when he gets up
You can see the necklace on Elio’s belly there.
I’m not sure if this was intended , but it’s most likely one of their improvised scenes. The necklace probably fell off by mistake and before they cut to the scene of them lying together Oliver had put the necklace back on bts.
abbys_little_whippersnapper 