- Scuba divers knew the layout of the station, there were ankle high of water and 2 of them are still alive, third died of unrelated causes;
- Legasov was talking to Scherbina about failures of evacuation during https://en.wikipedia.org/wiki/Three_Mile_Island_accident and not about how reactor works as it was common knowledge and Scherbina was experienced engineer who supervised energy sector in USSR;
- there were no forced labor neither for miner nor soldiers;
- miners knew and well respected Schadov, who was a miner himself. Needless to mention that he never came to any of the mines - there was a broadcast message that called for volonteers.
- Miners were enthusiastic and well compensated - they competed to go to the shaft. And they used proper tools. Documentary video exists.
- Vodka drinking in the middle of the harshest prohibition in Russian history. People could not get ANY alcohol for weddings still series shows vodka drinking on a high security object;
- Cherenkov radiation couldn't be visible in that situation;
- evacuation was swift and well organized;
- Legasov was not doing all the calculations alone he was a head of a whole institute;
- In helicopter scene Scherbina not only knew how reactor works but could not threaten Legasov as a) he can't order soldiers because chain of command b) Legasov has roughly the same political standing in USSR. Not to mention that Scherbina was quite nice person and was focussed on a problem at hand.
I can continue...