When Oleg goes to the grocery store to inspect wrongdoings, there is a Stalin picture hanging in the manager's office wall. Shortly after Stalin's death in 1953, the Communist Party started what historians now call the destalinization process to erase the legacy of the long time Soviet leader. Thus, it would be impossible to have a Stalin portrait hanging at the wall of a state-owned grocery store in 1984.
In Ljubljana, the sign pointing towards a library and a bakery says "Knjizara - iza ugla" and "Pekara - 20 m napred", which is Serbian. The correct Slovenian texts should be "Knigarna - za vogalom" and "Pekarna - 20 m naprej".
After Tuan explains to Pasha the proper way to bowl, he (Tuan) bowls a gutter ball, which the adults laugh at. Immediately thereafter, Alexei picks up a bowling ball as if to bowl. Yet Tuan has only bowled his first ball of the frame, so he should bowl again before it's Alexei's turn.