Hidden Side

El Fuego's Stunt Truck

A cannon-toting stunt rig and a chopper, tied to an app that no longer works.

Brick Rated Score

3.4/5

Set 70421 · 2019

Pieces429

Minifigs4

Year2019

Set number70421

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The verdict

This one is a bit of a time capsule now.

It was built around the Hidden Side augmented reality app, and that app was shut down at the start of 2023, so you're buying a straight physical set whether you like it or not. Taken purely as bricks, the suspension trick on the truck is genuinely clever and the four minifigs are some of the best-dressed in the whole theme. I'd get it for the play value and the figures, not for any lingering ghost-hunting gimmick, because that part of the experience is gone for good.

Best for: Hidden Side completists and anyone who wants a fun stunt truck build without caring about the dead app

The full review

What it is

I'll be honest with you about where this set sits. El Fuego's Stunt Truck came out in 2019 as part of Hidden Side, LEGO's big bet on mixing real bricks with an augmented reality app where you hunted ghosts through your phone camera. The truck itself has a neat trick built in: press a flap behind the rear wheels and the whole cab rises on a single hidden shock absorber while the chassis stays flat. It's a small piece of engineering that makes the model worth building on its own terms, cannon and all.

The catch

Here's the part I want you to know before you buy. The Hidden Side app was shut down for good at the start of 2023, so the ghost-catching mini games and the boss fight against Samuel Mason that this set was designed for are simply not accessible anymore. You're left with a solid stunt truck and a fun little three-wheeled chopper, but none of the digital layer that made the theme distinctive when it launched. Brickset's own review of the set called it their least favorite of the six Hidden Side models they built, describing it as bland compared to the rest of the line, even while praising the minifigures and the suspension gimmick.

Who it's for

Get this one if you're chasing the Hidden Side minifigures, especially El Fuego and the biker pair, or if you just want a decent two-vehicle build with a clever suspension feature and don't care that the app is gone. Skip it if you were hoping for the full augmented reality experience the box promises, because that ship has sailed, or if you want the more dramatic haunted-house transformations found in sets like the Newbury Haunted High School.

What works

Rear suspension mechanism that lifts the truck bed on a hidden shock absorber when you press a flap, and it actually feels satisfying to trigger
Four strong minifigures including El Fuego, biker duo Dwayne and Joey, and a ghost dog named Spencer, all with unique prints
Two builds in one box, the stunt truck and a separate three-wheeled chopper, giving decent play value for the piece count

Worth knowing

The Hidden Side app it was designed around was discontinued January 2023, so the AR ghost-hunting gameplay the set was built for no longer exists
Brickset's own reviewer called it their least favorite of the six Hidden Side sets, finding the model bland next to the rest of the line
No transforming or haunted-house gimmick like the flagship Hidden Side sets, so it can feel like a plainer vehicle set at this price

Sold? Grab it.

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The parts story

What the build is actually like, and the pieces worth knowing about.

The build splits cleanly into two halves: the stunt truck with its cab, cannon mount, and hidden suspension linkage, and a separate three-wheeled chopper with room for two riders. Neither build is long, so it moves at a decent clip, and the suspension mechanism is the one moment where the instructions ask you to slow down and actually understand what you're connecting rather than just following steps.

At 428 to 429 pieces (LEGO's own count and third-party counts differ by one), the standout here isn't rare molds, it's the minifigure lineup. El Fuego, Dwayne, and Joey all carry unique torso and leg prints you won't find recolored elsewhere in the theme, and the ghost dog Spencer is a fun oddball inclusion. The rear-mounted toy cannon and the compact three-wheeler frame round out a set that leans on character and mechanism more than exotic new elements.

Fun facts

01The set was designed to work with the LEGO Hidden Side app, letting you point your phone at the model to reveal an AR ghost-hunting layer, but that app was permanently discontinued on January 1, 2023.
02Hidden Side as a whole theme was pulled earlier than LEGO originally planned, largely because the brick-plus-app play pattern didn't sustain long-term interest the way the company hoped.
03The set retired in December 2020, just over a year after its August 2019 release, with an original US retail price of $39.99.
04It includes four minifigures, hero stuntman El Fuego, bikers Dwayne and Joey, and the ghost dog Spencer, alongside the truck and a separate three-wheeled chopper build.