Normally, only tiles with numbers up to #65519 are accessible, but if one uses animation on a high-numbered tile, one can include tiles #65520-65535 in the animation, even though they cannot be edited. If the number of animation frames is selected so that the tile would reference tile #65536, it instead wraps around to the beginning of the tile list and cycles through every single tile.
Perhaps a cap on A. Frames should be placed so an animation can't be long enough to access the "inaccessible tiles"? Here's a snippet of pseudocode that I think, if applied as a check for every combo, might solve the problem.
if (tileNumber + tile.aFrames) > tileList.size, then tile.aFrames = (tileList.size - tileNumber)