(Ok; I had searched the thread and didn't get any hits, so figured I'd note it.)
Do you know about the weirdness in Frostbite Tunnel in the icy-floor room, on the square you end up on right before the lady-in-red scene there? It seems that under certain circumstances (I have a save where I can repeat it, but can also disallow it from occurring by frex sliding back south & then north again), clicking that space makes a hidden-item noise, and doing so rapidly/repeatedly causes a 'found a master ball' text box to appear (and linger, though you can still move). Continuing to click causes 'found a great ball' texts (that also linger). No items are actually added, as far as I can tell. In a few instances (I think I moved around some first), there was a repeating movement-stopping 'qAF qAF qAF ...' text box. Other times, clicking made a walking-through-door sound and went to a black screen.
That square is bad juju, I tell you.
I can send a savefile/screenshots if necessary to showcase. My gut suspicion is that it's due to some leftover from the cutscene that plays (and that refreshing the square or whatever prevents the weirdness), but I'm no scripter, so I don't really know.