Taking the wrong route in any of the overtaking lessons stops the lesson from ending and stops the escape button from working so there is no way to get out of the game.
I've just tested it on the XFG 'Overtaking' traning session by crashing through the barriers where the RallyX circuit joins the back straight. I was sent to 'spectate' mode and some text appeared in the top left of the screen saying 'Not recording'. The escape key didn't work so I had to Alt-F4 out of LFS. I did manage to get back to the pits using Shift-P but the escape key still didn't work.
1 - Shift-R doesn't work in licences
2 - More of an omission than a bug. It doesn't say to press escape to exit the test drive as the parking area on the grass near the start line has gone in all of the tests.
3 - Also more of an omission than a bug. It doesn't tell the newer drivers what the pit lane speed limit is.
Getting that a lot, especially in the viewer... But also in the game. Normally just restarting LFS fixes it, but sometimes i need to change the graphics setting