ball on other side of net
 

Watched the UCLA-Hawaii match over the weekend and saw something I'd never seen in 30+ years of being around the game.

#5 receives serve, but dramatically overpasses to other side and on opposite side of court, still between antennae, but obviously going out of bounds. #2 ducks under net outside of sideline, reaches the ball at about the attack line extension and passes back (outside of antennae) to own team. #1 then shoots the ball to the serving side, but the ball is called out by a line judge because #1's hit went over the antenna.

So what would have been the correct call if someone from the serving team tried to play the overpass, but ran into #2?

It would have been interference if the serving team member interfered with a legitimate effort to play the ball. I believe the center line signal is the correct signal.

This sounds wrong...

It would be interference if the serving team tried to make a legitimate play on the ball that's on THEIR side of the net, near a sideline, merely because someone from the OTHER side of the net was also trying to play that ball?

Assuming a pursuable ball, yes. If the ball isn't pursuable (only in USAV and men's college, if there's enough clearance), then there's no fault.