Bad Export for You: As a deliberate means to prevent this, Hiroaki Samura personally redrew many pages so that the English-language release could be presented in the left-to-right English reading order without "flipping" the pages (i.e. mirroring them horizontally, a then-common practice which tends to cause this, especially with text).
Long-Runners: In his last author's note at the end of the final volume, Samura noted that he'd been writing Blade of the Immortal for nineteen years!
The Other Darrin: The 2019 remake has a whole new voice cast, though Manji's original voice actor, Tomokazu Seki, does show up as Master Sori.
The Film
Follow the Leader: Takashi Miike modeled the film's large-scale violence on 300, which had come out shortly before production began.