The Red Devils squad was called into a 3pm meeting on Wednesday as Mourinho assembled his players three days out from the Manchester derby with neighbours Man City this weekend.
All of United's stars were captured driving into the Carrington car park following the international break but Schweinsteiger, according to The Sun, took off in his black mini and snuck out the back.
The recently-retired Germany international has reportedly been frozen out by Mourinho but has vowed to stay at United and fight for his spot in the first team.
However, leaving the training complex just before a meeting is unlikely to have done him any favours.
Man Utd star banished from training and makes shock exit 15 minutes before start of meeting https://t.co/SYuK8ij3Kapic.twitter.com/ZB0ISG8VLC
— Sun Sport (@SunSport) September 7, 2016