You can use:
FlxAngle.angleBetweenMouse(Object:FlxObject, AsDegrees:Bool = false);
FlxAngle.angleBetweenPoint(Sprite:FlxSprite, Target:FlxPoint, AsDegrees:Bool = false);
for setting angle of object.
Then set velocity from angle. use FlxVelocity.velocityFromAngle();
Don't forget to set gravity (so the object can fall) object.accerelation.y = 100; // gravity
Now if I had a canon that was launching said FlxSprite in an upward direction, would the velocity be accounted for? I guess what I'm trying to say is, if I launched the object almost completely upward, would the velocity towards the left or right be minimal?