"Crisis on Earth-X" Had a Nod to the Richard Donner 'Superman' Movies

Spoilers ahead for "Crisis on Earth-X," which airs tonight.

In its final hour, the "Crisis on Earth-X" DC crossover special featured an homage to Superman II.

The crossover, which brought together characters from Arrow, The Flash, Supergirl, and DC's Legends of Tomorrow to battle against invaders from an alternate Earth, was flush with pop culture references, allusions to other DC properties, and more.

The Superman II reference came when, as she is preparing to confront her Earth-X doppelganger for the last time, Supergirl flew up to the Wellenreiter (Earth-X's Waverider) and said, "General, would you care to step outside?"

In the context of "Crisis on Earth-X," Earth-X's Kara -- Overgirl -- is a general in the Nazi army which rules Earth-X. The reference to Superman II came moments after the famed "Kneel before Zod" rant, when Superman approached General Zod from outside of the Daily Planet.

While Tyler Hoechlin's fan-favorite take on the Man of Steel did not appear in "Crisis on Earth-X," he was well-represented: during an argument with Supergirl, Eobard Thawne recounted having fought Superman; and Thawne also made what sure sounded like a reference to a latter-day episode of Smallville.

With black outfits and jackboots, Zod and his Kryptonian minions seemed fairly Nazi-inspired even in the '70s -- so it would stand to reason that when facing off against a similarly-attired Kryptonian who holds the same military rank, the writers might take an opportunity to pay homage to what is widely regarded as one of the big screen's best superhero/supervillain punch-ups.

"Crisis on Earth-X" began last night at 8 p.m. ET/PT and runs for two hours beginning at 8 yesterday and today. Unless you have an easy way of getting caught up on your DVR, hang around and first thing in the morning you can buy digital copies on iTunes, Vudu, and other digital streaming services -- or watch it for free with ads on The CW's website or app.

The CW's DC superhero series will return with their midseason finales next week, beginning with Supergirl at 8 p.m. ET/PT and continuing with The Flash (Tuesday at 8), DC's Legends of Tomorrow (Tuesday at 9) and Arrow (Thursday at 9).