Tesla’s electric pickup truck, the Cybertruck, certainly hasn’t had a quiet introduction. Its design has invited several interesting comparisons and critiques, as have several of its features. Especially the Cybertruck’s supposedly ‘bulletproof’ windows, which broke twice during on-stage demonstrations with thrown steel balls. Elon Musk may have quipped it away, but he may have feared the incident would shatter trust in the Cybertruck.

So, shortly after the reveal, he tweeted out a video showing a Tesla employee hurling another steel ball at one of these windows—and the glass didn’t crack. But even so, several individuals have cast doubts about Elon’s claims. And even ignoring all the controversy, there is a serious safety issue that has to be raised about the Tesla Cybertruck’s windows.

Why Musk said the Tesla electric pickup’s windows shattered on stage

Part of the Cybertruck’s reveal was testing the durability of its design. Tesla Chief Designer Franz von Holhausen first took a sledgehammer to the door of an aluminum-bodied F-150, then the Cybertruck’s stainless-steel door. The F-150’s door dented, the Cybertruck’s didn’t. But, according to Elon Musk, the Tesla pickup didn’t walk away unscathed.

In a tweet, the Tesla CEO claimed that the sledgehammer blows cracked the window glass below the door. This made the glass weaker, allowing von Holhausen to break it further with those steel balls.

To assure the public and Tesla fans, Musk then tweeted out a video showing von Holhausen hurling another steel ball at the Cybertruck. But this time, the window doesn’t crack. Musk claims that the video was taken “right before launch.” However, as The Drive reports, several things about both the live reveal and the follow-up video aren’t adding up.

The ‘bulletproof’ window controversies

To be fair to Tesla and Musk, as we will show in a moment, even bulletproof glass can break under hard sledgehammer impacts. Although this explanation implies the prototype had some quality-control issues, it isn’t out of the realm of possibility. That being said, many people aren’t buying it. For one, The Drive points out that von Holhausen hit the front driver-side door—but the balls were hurled at the rear door. Why would the Tesla Cybertruck’s front door being hit crack the rear window?

And secondly, several people are claiming that von Holhausen’s orange sledgehammer was actually a soft-headed dead blow hammer. This type of hammer is meant to pound sheet metal without causing unnecessary damage and typically comes with an orange head. But this latter claim is difficult to substantiate without an inspection of the hammer itself.

Then there’s the follow-up video. Initially, some were skeptical that the video was actually made beforehand, but it seems that it really was. But the bigger issue is with the blanket. Some have put forward that it’s in place to protect the door in case of a miss. However, because the video is in slow-motion, one Twitter user spotted the door appearing to move after impact. The blanket, said commenter put forward, wasn’t only to protect the door. It was to disguise that the door wasn’t latched, which would let the whole panel absorb the blow without risking another window break.

The safety issue with ‘bulletproof’ windows

Ignoring all the claims and counter-claims, it is apparent that, to paraphrase Musk himself, Tesla still has some work to do. But for the sake of argument, let’s say the Tesla Cybertruck’s windows were actually made bulletproof. That would actually cause a huge potential safety hazard. Not for someone trying to get in, but for someone trying to get out.

According to Total Security Solutions, fully bulletproof glass would be difficult to see through. But bullet-resistant glass (which is most likely what Tesla means) isn’t just glass. It’s usually made out of either solid acrylic plastic or by sandwiching polycarbonate plastic between sheets of tempered glass. It’s the plastic that absorbs the bullets—and, as ESG-Glass demonstrated, sledgehammers.

Which is fine if you’re getting shot at. But what if a baby is trapped inside a Cybertruck on a hot day? Or, what if you drive your Tesla into a river, and you need to smash the window to get out before you drown? Car window breakers are available, and they are excellent for smashing automotive tempered glass. But, as The Drive has pointed out, they can’t fully break through bullet-resistant glass. Yes, bang on the glass with a big sledgehammer enough times, and it will shatter and fail. But that takes precious time.

This all presumes the production Tesla Cybertruck will actually have bulletproof (or bullet-resistant) windows. At the moment, that’s unclear. But Tesla will have to consider these kinds of issues before the Cybertruck reaches customers.