It was exactly how it happened - read any account of WW2 on the Eastern Front and human wave attacks by the Red Army are repeatedly mentioned - there's a reason why the Soviets suffered such heavy casualties in WW2. The NKVD were frequently stationed behind attacks with machine guns 'pur encourager les autres'. Both sides shot people for retreating.
Your jumbled perception is pretty standard, so does not suprise me in the slightest.
Whilst the massed attacks were used to a ridiculous extent in 1941 and later on by pig-headed commanders like Zhukov (who was an absolute f*cking pr!ck and at the time of Stalingrad was losing thousands of men in front-on attacks on other sectors of the front) and I understand the director's desire to include that, the way it was done was just majorly inaccurate as
1. No matter how much one likes the idea of Russian charging en masse across a square getting machine gunned, this would've occured on a very small scale in street-to-street urban fighting - in fact, it was the Russians' skill at the said street-to-street fighting that meant that the Germans foundered at Stalingrad.
2. Again, the idea that many silly peasant Russians went forward at gunpoint at the insistence of gun-touting commissars is a very heart-warming one that was actively cultivated during the Cold War but is not entirely accurate as what tends to get overlooked was that "zagrad otryady" were not sat en masse in trenches with machine guns pointing at the soldiers' backs - the primary task was to be positioned some distance behind the front line and stop the soldiers pegging it if there was a breakthrough, for example, or redirecting and reforming broken up units.
Yes, this was also done via executions, etc but if you actually look at the stats - these numbers are pretty low and certainly did not amount to indiscriminately spraying the retreating troops with bullets.
3. Penal companies (batallion-strength units formed too) - these were effectively death squads, survival chances close to zero and these were often unleashed before the general attack to basically look at the Germans' patterns of fire and to prode their defences. These were not allowed to return and would often be shot if they turned back. The on in "Enemy at the Gates" did not strike me as a penal unit. There were officers' penal batallions who - if not quite sent over the top - were basically sent on the most dangerous hopeless missions. There were other penal units that were sent on reckie/sabotage missions behind the enemy front and the survival rates in these were higher. Of course, if you survived a certain period of time, you would be transferred back to a regular unit.
Of course, there were horrendous cases when penal units actually took the first German trenches but as they weren't really expected to survive, they would then get flattened by the Russian artillery bombardment - read account of the one in Yassy in 1944 - absolutely horrendous.
