Dortmund had gone into the last game of the season in top spot but stumbled to a 2-2 against visitors Mainz 05, allowing Bayern to squeeze past them in the tightest league race in years.
Browsing: Jamal Musiala
Sven Ulreich, Eric Maxim Choupo-Moting, Leroy Sané, João Cancelo and Thomas Müller, among others from the professional squad joined the session.
Robert Lewandowski gave Bayern an early lead before 17-year-old Jamal Musiala scored his first Champions League goal on only his fourth appearance in Europe.
In a typically ruthless Bayern performance, the prolific Poland forward struck twice in the first half hour and added a third after halftime before substitutes Leroy Sane and Jamal Musiala completed the rout.