On the chess board shown at the beginning (and then again later in the movie) the main character promotes the pawn to a knight which both he and the computer claim is a checkmate for black. It isn't a checkmate, since white can then take the knight with the bishop. There is a mate in three for black (rook to g2, white is forced to move the king into the corner, rook to a1, white is forced to interpose the bishop, rook takes bishop = checkmate)
When reciting the contents of the cabinet on the wall to the Doctor, Clay says he is reading "top to bottom, left to right", but the six bottles of peroxide he mentions last of the things he recites are in the top left corner.