Seeds or bulbs planted sideways or upside down will still try to grow the right way. The problem with bulbs, though is that they are often several inches below ground, so if they expend energy trying to make a 180-degree turn, that could hurt the plant a lot. Now I don't know if that could go another season...I know some bulbs seem to reposition themselves at a certain depth so they might right themselves up too.
But for seeds which are often just 1/8 or 1/4" below the ground, they will probably be OK if not planted the right way. Case in point is how we often drop tomato or pepper seeds into a seed tray. Generally it will fall flat but it could fall in some other way. It will still grow OK.
