Nobody there with the wherewithal to bust the doors open?
The handcuffs are only handcuffs and can only take so much strain.
They could have been hinged cuffs.
Doesn't everyone carry a handcuff key?
I've been carrying one more than 30 years. Almost all cuffs use the universal key, which is readily available online (coff, coff, Amazon, coff). Only costs a couple of bucks and takes up almost no room in your wallet. With it in your wallet in a hip pocket you can still reach it with your hands cuffed behind your back. When I've worked overseas, I had several pairs of slacks with a key sewn into the hem of a hip pocket.
If a door is secured more substantially than by handcuffs, I've DIYed some 12-gauge breaching shells with an ounce of lead filings (each) suspended in molten paraffin. It leaves the barrel like a slug but shatters on impact into harmless iron filings. I've got a dozen of them on my shotgun shell bandolier.
If you want to open it with less noise, you can DIY a breaching tool from a Fat Max with an angle grinder.