Chris Pratt steps on Arnold Schwarzenegger’s greatest line, emerges as ‘Tomorrow War’ alpha hero

When the first trailer for "The Tomorrow War" was released in May, Chris Pratt felt the unveiling of his full-throttle action film required an apology of sorts to his father-in-law (and action icon) Arnold Schwarzenegger.

"Just to save the embarrassment, I prefaced showing the trailer by saying to Arnold, 'I have a line in this trailer where I say, 'I will be back,' " Pratt recalls contritely confiding about veering close to Schwarzenegger's iconic "I'll be back" line from 1984's "The Terminator." "I recognize that it really pales in comparison. You made that line so iconic. And for me, it just sounds like a dad who's going to the store."

Whoa, just stop right there, soldier. Pratt's promise to return was for story, not challenging the movie god of one-liners.

The fact is, the "Guardians of the Galaxy" star, besides being starry-eyed over his wife, Arnold's daughter Katherine Schwarzenegger, has never been more action-awesome than in the sci-fi adventure (streaming on Amazon Prime Friday).

Even Pratt is compelled to agree. "The movie is essentially a highlight reel of every time (a stunt) worked on camera," he says. "It makes you look pretty cool."

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Here's how:

Pratt drops into action, firing while holding his rope!

Pratt, 42, plays high school science teacher Dan Forester, who's conscripted and sent to 2051 to help humans avoid extinction from the massive fangs of ever-devouring space aliens called White Spikes. Forester's military combat experience allows him to go full throttle, including one scene where he drops from a helicopter into alien battle.

He holds a rope in one hand and fires his gun with the other before dropping into a White Spike lair.

The descending stunt was performed in a Georgia rock quarry. Pratt watched the Navy SEAL instructors pull off the stunt first.

"I was like, 'How am I supposed to do this? Going down the rope and shooting the gun the whole time, I'm going to want to burn my hands off.' But we made it work," says Pratt.

As he descended, director Chris McKay zoomed in with a camera perched on an approaching dune buggy as smoke canisters and the setting sun enhanced the drama. "I remember that camera moving up close, and I'm shooting this automatic weapon before dropping down into the hole," says Pratt. "And I thought, 'That's pretty iconic.' "

Pratt put loads of lead in an alien coming down the wrong hallway!

Pratt, who's now filming Amazon's upcoming Navy SEALS series "The Terminal List," trained with SEALS for "Tomorrow War." There was an emphasis on effectively reloading and switching firearms to take down the relentlessly approaching White Spikes.

In a heated hallway with a White Spike, Pratt's Forester emptied his automatic weapon clip, then switched rapidly to his handgun. While the computer-generated alien was added later, it's drop-dead shooting.

"My gun went empty, so I transitioned down to a pistol and emptied both guns at this alien, all in one take," says Pratt. "That was one I was really proud of, where the SEALS came up, gave me a pat on the back and said, 'That was great.' I was pretty pumped."

Pratt’s action glare smolders!

Pratt has a cool action resting face that gets even more intense when he's firing. When that smile turns down, it's an action gift.

"You're not supposed to blink your eyes when you're firing a gun," says Pratt. "So I end up squinting so (stuff) doesn't come into my eyes. And squinting my eyes, it just makes your (face) chomp down. So it just happens to naturally make that look."

McKay even used a special high-speed Phantom camera to capture slow-motion battle shots locked on Pratt's face.

Pratt pummeled frozen glaciers with his face!

During a hasty expedition to Russia to track down the White Spikes lair, the action turns icebound, as flying snowmobiles crunch into White Spikes. Shooting on location in Iceland, Pratt impressed McKay with his willingness to eat snow on glaciers after being propelled from all sorts of explosions. During one pivotal big boom, "He was running and did a massive leap and then threw himself face-first onto the frozen ice," McKay says.

"So we got that shot down from differing angles. You see Chris come up and his face is covered in snow. Chris wanted to make the movie very visceral."

Arnold came to appreciate the action (and heart)

Schwarzenegger was impressed with the sizzle reel.

"He was like, 'Wow, that was an incredible trailer,' which it is," says Pratt.

But Schwarzenegger ever-sagely discussed the emotion, and Forester's relationship with the daughter (Ryan Kiera Armstrong) he has to leave behind to fight aliens. Yes, the daughter to whom Forester said, "I will be back."

"(Schwarzenegger) said, the key to these movies is the relationships. And it's true," says Pratt. "The movie has time travel, aliens, action and one-liners. But the emotions and heart sneak up on you."

Schwarzenegger can also take heart knowing his son-in-law can surely protect his family from a real deadly alien attack.

"And I can fight off aliens," Pratt vows. " As long as I get 10 cracks at it where I can yell, 'Cut' in the middle of it, we'll be just fine."

This article originally appeared on USA TODAY: 'Tomorrow War': How Chris Pratt steps on Schwarzenegger's best line