The text on Joshua Graham's pistol, A Light Shining in Darkness, is Greek. It reads "καὶ τὸ φῶς ἐν τῇ σκοτίᾳ φαίνει (kaì tò phõs én tẽ skotía phaínei)" on the right side and "καὶ ἡ σκοτία αὐτὸ οὐ κατέλαβεν (kaì é skotía aútò oú katélaben)" on the left side, which translates as "And the light shineth in darkness and the darkness comprehended it not".

New Canann, the town where Joshua Graham and Daniel hail from, was named after the land promised to Abraham and his followers in the Bible. This is likely due to the people of New Canann being Mormon.

Though not an exact replica, the .45 auto submachine gun in the Honest Hearts DLC is based off of the Thompson submachine gun.

Most of the Honest Hearts Tribals speak a creole language.

The Dead Horses' language is based on German, English, and Navajo, although the morphology of the Navajo is unrecognizable.

The White Legs speak a combination of languages from tourists and locals in a place called Res.

The Sorrows language seems to be a combination of broken English, German, Spanish, and hints of Japanese.

During the initiation of the final part of the companion quest "ED-E, My Love", a glitch could occur where Senior Knight Lorenzo's dialogue can be randomly replaced with a placeholder version of the voice line. This placeholder line was performed by producer and programmer Jason Fader, who was asked by area designer Akil Hooper to provide two very different temporary voice lines for ED-E's broadcasts of Lorenzo and April Martimer's voices. Fader performed Martimer's voice with an impression of the horror character Count Dracula, and performed Lorenzo's voice with an impression of Inigo Montoya from the 1987 film "The Princess Bride". Although these placeholder lines were removed from the final game, one line of Fader's Inigo Montoya impression could still be heard in-game if a certain flag in the game's code was tripped. Fader's father discovered the bug through gameplay footage on YouTube and brought it to his attention as he recognized Fader's "dumb voices". Fader recalled that commenters on the YouTube video shown to him flatteringly questioned why a Mexican voice actor was used for only one line in the game, oblivious to its origin.