it was a combined assault of the 268th, 136th and 86th Rifle Divisions. Only the 136th Rifles had a band playing International. In the movie it is shown in a wrong way - according to accounts of the veterans, the band was in the trenches, not standing upright. The 136th Rifles became the 63rd Guards Rifles for the participation in operation |Spark.
well, a good reason to have a remake of that movie

There are plenty of other flaws in the old version...
Red Army greetings,
Bair