In "Bread & Circuses," Spock refers to 6 million having been killed in WWI, 11 million in WWII (and of course 37 in WWIII). A 1965 Almanac gives 8.5 million & 26.6 million respectively (those being troop dead, with no inclusion of civilians), which means the figures cited could easily have been checked and found wrong at the time.
In-universe, this suggests an alternate timeline predating WWI…but has anyone speculation (or better) as to how the mistaken figures made it to the air? Fact-checking in Season One is on record, and lawyer-checking, at least, in Season Two (as in the Gerrold's flatcars, eh, tribbles). Was late Season Two so rushed as to explain these errors?