Con Smith's headphones are the audio equivalent of Psycho Mantis' gas-mask.Con's super-hearing is so super that he needs to wear special headphones to be able to hear anything other than migraine-inducing noise.
Travis Bell is a deceased Travis Touchdown.Travis Bell is a "killer who got killed on the job", and has an attitude that's quite a lot like Travis Touchdown's. Also, he wears a lot of fun t-shirts. It was never actually stated what year No More Heroes takes place in, either! Though I'm pretty sure Suda 51 debunked this somewhere... To expand on this, Travis was killed by Garcian at the end of No More Heroes, while doing a shit. What a way to go.
The Heaven Smiles only look that way to the Killer 7.When seeking out Andrei Ulmeyda, the girl in the post office mentions being annoyed at the number of creeps with the weird smile who have moved in lately. She doesn't apparently see anything odd about the fact that they are inhuman monsters. Furthermore, in the scene explaining how the world has changed at the start of level 2, the Heaven Smile that attacks the UN summit just looks like a normal person with a freaky smile. Evidently, the Vision Ring allows the Smiths to immediately tell who is a Heaven Smile and who is not.
Coyote was once a member of Andrei's cult. In the mission to meet Andrei, if you select Coyote on the TV screen, he gives a spiel about how "this is the moment I've been waiting for. I have to do this or the anger inside will not go away." The only other character who gets a speech like that is Dan, when on the mission to terminate Curtis. Also, Andrei's base is in Texas. Since Coyote is Hispanic, he probably passed through Texas when he emigrated; either that, or he was born in Texas, which does have a high Hispanic population. Finally, the cult member who replaced Iwazaru on the Andrei mission looks an awful lot like Coyote; it's hard to tell with the art style, but I think he is supposed to be Coyote, perhaps before being recruited by the Killer 7.
Con isn't blind at all, just apathetic.Con's blindness is a metaphor for the innocence/apathy of children: His eyes don't care to process the very adult situations their owner is thrust into throughout the game, but can easily see things a child might enjoy. Supporting this is the fact that he very clearly sees the Handsome Men, Sentai knockoffs and heroes of a popular children's television show, striking their poses.
Killer 7 takes place in HellEveryone is already dead and they're all being forced to relive this whole mess again and again in Hell, with more mind screws every time around, for eternity. Or at least until Armageddon. This is really the only way to make sense of this whole game and consolidate it with the expanded universe materials and promotional materials. It also explains the bookending, Killer 8 Mode, and and Hopper 7 Mode.
Kun Lan's was influenced by the Joker.Compare Kun Lan to the Joker as presented in Batman: The Animated Series and the 1989 movie, which would be the most familiar to a Japanese audience. Both have deathly white skin, green hair, weird eyes, and an insane laugh. While Kun Lan may not have an evil smile, the Heaven Smiles sure do. Also, both are completely insane.