Now, THERE'S a poster that actually spells "Samurai" right!
It's not an official poster, it's just something the seller made. Not that there's anything wrong with it. I do have an official Saban poster that has it spelled right. On the opening credits of the show, they used a picture of an eye on the letter "i" rather than spelling the "ai" part, but that seems to have been done intentionally to go with the song, since it's spelled right every where else.