The dueling circle arrow is bugged while spectating a match. When the turn ends, the arrow stays at the person or minion who last cast a spell. Yes, it does keep the order of who's first and who's second when another turn starts, but it's really confusing if you aren't aware of the problem. (if you're in the match, the arrow works fine, it's just the spectators who encounter that visual glitch)
Also, when someone casts a spell, the spectator view shows that the caster uses said spell, but it does NOT show on who it is used (it used to do that but now it's bugged).