I don't think anyone has hit it yet and if Disney did their job properly, it's unlikely anyone ever will. From a display standpoint, the screen can at a minimum show 9,999,999 but most people cannot even get more than 400K consistently as a single player. If anyone has gotten more than 1,000,000 as an individual, it would be interesting to see if the display can show that. From a back-end programming standpoint, the maximum score has not been hit yet. Don't forget that Disney learned from Astro Blasters that they needed to have more display and bits to show the score so the maximum score has not yet been reached in recent rides like Ant Man in the Wasp in Hong Kong.