"I understand there is a movie making the rounds about Joplin's last series of concerts in Canada..."
There is, it's called FESTIVAL EXPRESS and it's a blast. Not only Janis (three months before her death), but the Grateful Dead, The Band, Buddy Guy, etc. are captured in live performance and hanging out on the train. The promoter was a character in his own right and lots of interesting things occurred along the way.
If you like music see it.
Levon Helm, by the way, did a great job as Sissy Spacek's father in 'Coal Miner's Daughter'. He was perfect! Is he still around?
'The Last Waltz' was so fine.