Final Fantasy VII -052- Diamond WeaponChrist, the people are Square really have a poor sense of direction, don't they?:
"When the Sister Ray is fired from Midgar, it destroys the barrier over the Northern Crater. However, if one flies (in the Highwind) from the cannon in a straight path toward the Northern Continent, they will miss the crater by a number of degrees.
That Diamond WEAPON might have redirected the Sister Ray's shot is unlikely, since the related FMV shows the shot going straight through the WEAPON, without changing direction (there's also the matter that Shinra wouldn't have planned for the WEAPON's presence)."
(http://www.ff7citadel.com/secrets/s_errors.shtml)