They stopped for the night when the thick darkness dawned on the forest.
had downed

Plot:
They decided not to build campfire because it might attract the pursuers
later:
After the lesson they all shot a tree
They didn't bother with the noise?

Peter finally changed his clothes covered with gore blood
Personally I would do that before I sleep. And also I'd tried to find some water to wash.

they had little breakfast
Did they take some food with them?

then packed things and started on their way back
Peter insisted that they carry a recon they have a look around so they had to spend another hour just sitting at the edge of the forest and observing
Everything seemed to be alright given judging by the villagers wandering around here and there, even despite their slightly depressed look.
I think nothing was allright. All communists and jews should have been hanged or shot by now. Several women were raped. Yet you say 'everything's allright' Not to mention that some reprisals for a dead soldier should have taken place.

At sometime when they were sitting at the edge of the forest, Ann came crawled over to Peter and sat beside him.
Then I’ll go to the Minsk airport. When on board...
‘You’re kidding joking, right? Even if we forget for a moment that there’s kinda this little war around, still you’re talking nonsense.
Ann could not possibly know the words 'kidding' or 'kinda' in 1941. They came into use much much later.

there are no planes in the world that can cover such a distance between us and the United States over the ocean. They will simply run out of fuel... (later) The airflow will just tear the hose apart
She's surprisingly well-informed for a rural linguist. Is she a physicist also? Airplanes were still a wonder at that time. Pilots were all heroes. 'Stalin's falcons'.

she giggled
Personally, I don't think she was able to giggle after all that had happenned the day before.

Sorry, but it looks like a fantastic story, sort of like those about the Martians and UFOs
Flying saucers first appeared long after the war. She wouldn't know what UFO is.

How will the a plane share is its fuel?
‘I don’t think old Nikolai and his wife are daydreaming of saying thanks to me for what I’ve done to their house.’
Oh, don't worry, Peter. They both quite likely are dead by now.