Actually the term "Manslayer" was not cartoon network's idea but Anime Works.
Jin-e is not a "battosai", but a hitokiri, which means assassin in Japanese, or as Cartoon Network puts it, "man slayer".
Battosai is the nickname given to Kenshin because he has mastered all aspects of the battoujutsu techniques, that of starting the sword in the sheath to increase the speed of the attack.
In the Akabeko there is a leprechaun dining in the backround. Leprechauns are Irish, not Japanese.
Before Kaoru gets saved by Kenshin, the cut given to her by Battousai on her right arm was bleeding, but now after Kenshin does save her, it is not.