It's actually possible to get an infinitely high score in level 252. It's a timer-based level with only 4 colours, so you can get +5 bonuses faster than once every 5 seconds, extending the game indefinitely. My max score is 3.5 million+.
In the iOS version, levels 609 and 619 are the same. So are levels 608 and 623. I'm not sure exactly how much the same, just the layout or even the type of level, target score and number of moves. This is really stupid design. If you're going to copy levels, DON'T PUT THEM SO CLOSE TOGETHER! It's even worse because 608 is also used as one of the quest levels in the jump between 608 and 623, so you see it 3 times. They say they've since changed it, but I don't think they'll change the iOS version.