A desert somewhere in Equestria
"Hey, we're going the wrong way! The base is that way!" said Josh to the pilot.

"Sorry, sir. I'm only taking orders from captain Shining Armor!" said the pilot.

"Well, where are you taking us!"

"Almost there!"

The pilot stops the chopper while in-air and hovers while waiting for a huge door opening on the desert bed.

"Holy shit!" yelled Kay, "I don't you guys have an underground base here!"

"Kay... I don't know any of this.." said Josh.

"I though you're the captain!"

"Just because I bring rifles to Equestria doesn't mean I know any of this!"

"This is Seirra 2-0. We have VIPs onboard, preparing to land." said the pilot to his comms, as he safely landed the aircraft on the helipad. The heroes set their foot on the ground and looks around where they're greeted by Twilight Sparkle and Shining Armor.

"Kay. Yuri. Good to see you again." said Twilight to the two.

"You look very stunning, Princess Twilight." said Yuri.

"Just Twilight. We're friends, remember?"

"Da."

"Twilight... What is this?" said Josh in confusion.

"You are now inside The Cave, captain." said Shining Armor, "This facility is specially build for production of superweapons and creating magic with advance technology."

"Superweapons? Magic?"

"The weapons are still underdevelop. But when it comes to magic, we have ups and downs."

"But we succesfully create a portal which generates the same magical elements as the mirror." said Twilight.

"Come. We'll show you guys our latest invention." Shining Armor escorted the two, with Josh and Twilight walk together behind them.

"A little science project, uh?" said Josh.

"It's my brother's idea. I'm just helping him out." said Twilight. "Besides, you're too busy monitoring rebel activity to notice."

Front of them, Kay notice the two started arguing.

"Looks like the happy couple started it again." said Kay.

"Is it always like that?" said Shining Armor.

"Probably. Someone need to teach them how to love."

"Trust me, Kay. Cadance tried that."

"Speaking of love, the two ever had sex?"

"She never said anything about it, nor to Josh."

"I'll take that as a no."

After their argument, the two then joins the other three.

"Sorry for keeping you guys waiting." said Josh, "Now. Can you show us your little science experiment?"

"Sure. Right this way." Shining Armor leads them to a second chamber, which houses a large teleporter plugged to the main power source.

"Little science experiment? That looks like a big ass machine!" said Kay.

"It's more than just a big ass machine. It's a teleporter that generates the same energy as the original mirror. With the right amount of power that is." said Shining Armor. "Now, while we powering it up, you three should get ready."

"A'ight, where's the armory?"

Armory
Like a couple of kids in a toy store, Yuri and Kay oicked up any weaponry they can get their hands on.

"It's been awhile I smell scent of guns." said Yuri, "I've been smelling fabric since I help my wife with her boutique. It's good to stay away from it all. Not good for mind."

"This is just a start, man. In any moment, we're going to sniff burning lead and flesh." said Kay while carrying a M249, "This gun brings me back when I rob my first bank."

Then, Josh entered the armory to see them.

"Guys, I had a discussion with Twillight and-" Josh got cutted by Kay.

"Was it a discussion or an argument?"

"Let me finish. We had a discussion and I'm sorry to say this, but we can't bring heavy weaponry."

"Que?! Why!"

"Look, as much as I disagree with her, but I don't think bringing that much weaponry would be a good idea."

"And then you two had argument?" said Yuri.

"Can you guys stop- Yes, then we had an argument, and you and I know who won."

"Then what are we suppose to do?" said Kay

"I'm guessing we'll just bring smaller arms, like handguns. Concealable ones."

"Good thing I brought this beauty." Kay pulls his Deagle from behind which surprised Josh.

"W-where did you pull that out?" said Josh.

"Hey. It's concealable, right?"

"I didn't bring my gun. Can I hold this gun for awhile?" said Yuri while loading a TMP.

"As long as you guys don't fire the gun unless you have to!" said Josh.

"Hey, we know rules of engagement." said Kay.

"That reminds me," Yuri face his looks at Josh, "What are we fighting?"

"Paramilitaries," said Josh, "The rebel's been supply them with enough weaponry to start a war. Why they used the mirror, I don't know. But Twilight insist on going to the other world and stop them."

"Interdimensional warfare?" said Kay.

"We'll know once we're get there."

"Great. Now that's outta way, let's talk important matters now." said Kay.

Portal Chamber
As the portal powers up, the three heroes prepare themselves before Twilight joins them.

"I think it's better if I go along with you guys," said Twilight, "Trust me. It's a strange world."

"Exactly, how strange?" said Josh.

"Unbearablely strange."

"This is going to be fun" said Kay.

"Portal's ready! The gateway is open! You are clear to jump to the portal!" yelled Shining Armor.

"Let's haul ass!" Josh gives the orders and all of them jump to the portal and disappears.

"It works? I can't believe this at first, but it works!" said Shining Armor. "Get a chopper ready, I wanted to discuss security update for the Crystal Kingdom."

Author's Note

I know, it's been like months now and it's 2014 and non of those stuff in Back To The Future Part 2 are even made.