Hard to pick just one, but here are a couple of highlights :
Driving some Interstate (don't recall which one) in Dad's 58 TR3A, nearly 1000 miles from home. Wasn't paying good attention, almost passed the ramp, started down the ramp at nearly 80 mph. Car lurched violently left then right, almost turning over. The nuts that hold the splined adapter to the left rear hub had come loose, and two of the studs were broken off. Tightened the remaining nuts with a pipe wrench (they were too far gone to get a lug wrench on them) and drove cautiously to my destination (a friend's house), then had Dad ship me a new halfshaft & hub.
That was over 30 years ago; ironically Dad just had the exact same problem on the same car a few months ago! But he didn't happen to take a ramp too fast at the right time, and didn't notice the problem until the wheel parted company with the car. He's got some damage to repair.
Descending a mountain at 80+ mph in my 59 TR3A about midnight; lost both headlights. Fortunately on a relatively straight stretch of road and little traffic, so I was able to stop on the pavement, let my eyes adjust to the limited moonlight, and pull to the side. Installing a spare fuse got me on my way.
Driving the 71 Stag to the shop to have the MC replaced, MC quit working totally. Continued on using the handbrake, but the rear brakes overheated so that at the final exit off I-10, no way to stop. Sailed right through the intersection, fortunately no one coming. Let the brakes (and driver!) cool, then continued to the shop, using lots of compression braking
Stopped at a motel roughly 600 miles from home in the 3A. When I went to move the car to the room (a railroad car), it didn't want to start. Presently black smoke started rolling from under the hood. I thought it was on fire!
But it turned out to just be a bum starter drawing too much current, the smoke was just the insulation on the battery cable. Got some friends to help push-start in the morning, and continued home. That was the incident that convinced me I wanted a gear-drive starter