In "6955 kHz", a shapeshifter refers to "all's fair in love and war" as "something they say on this side," implying that they don't say it on the Other Side. Google tells me that the phrase can be traced back to Lyly's Euphues, published in 1578.
Is there anything older than this saying which is different on the Other Side?
I've only watched through "Entrada", so if people could spoiler-tag anything that comes later than that I'd appreciate it.