- Unintentional Period Piece: Kun Lan tells Harman at the beginning that the world has changed to the point where one "can control it with their hands just like a PDA", which dates this game back to the early 2000s, back when PDAs were popular before smart phones took over. (However, this double-unintentionally still works in-universe, since the internet in the game's world is banned/underground, thus PDAs would still likely have been popular.)
- What Could Have Been:
- Some of the earliest trailers had different character designs for the crew, and (possibly) the plot would have been different. Kaede wore a white collared shirt and pants, Garcian was thicker and didn't have the goatee, and Heaven Smiles were not zombie creatures, but berserk humans with joker faces.
- The book offers up an entire comic made out of screenshots regarding a beta version of the Curtis plot. In this version of the game, we would apparently get to see Dan's apprenticeship, death, rebirth and revenge. In the final version of the game, all this is instead backstory, excepting the revenge which takes center stage. Sundance Shot shows up briefly in this comic, seeming to imply that killer7's plot may have been more closely linked to the other Kill the Past games.
- There are also hints that the game was going to be a lot bigger, with The Art of Grasshopper Manufacture revealing that there were originally four hours worth of storyboards drawn up for cutscenes, and they decided to cut it back to only an hour and a half.
- Because of Suda's style of writing, where he comes up with the plot and then builds the game around it, there are major characters and plot points in the wider scope of the game's universe that either barely or never appear in the game itself. All There in the Manual material like "Hand in killer7" mentions a lot of them, but aren't Mind Screwdrivers.
Trivia / killer7