On a corner it's possible for a pawn to move OR attack the same square, because the pawn can reach the square by moving to it directly or indirectly, with the indirect path corresponding to a "diagonal" attack.
If there is an enemy piece, only the attack is a valid move, but sometimes the invalid move indicator appears over top the valid move indicator. The valid move indicator should get preference.

Actually, this should no longer be possible if I implement truncated cuboctahedral board geometry, I think.