Yes, this happened many times, mostly due to ignition problems.
For instance when I went to Elvington in 2005, the small axis on the electronic distributor broke and a wise garage man between Dover and London made a similar pin from a strong piece of steel rod .
Once, I had to make 100 miles stuck in 3rd gear before reaching my garage.
Another time, I had to do 500 miles with a slippery clutch (I burned the disk during the drag races) that allowed me only 2000 rpm going back home. Both clutch and alu flywheel were dead and now, I always have at home a spare clutch and flywheel waiting...
A glorious one was when both the starter and the ignition box failed. Nice policemen offered me to push the Cobra to start but this had been useless as I knew it would not fire (thanks, otherwise I might have had problem if they had hear the sound upon starting!!!!)
Since, I always carry a spare new starter and ignition control box in my trunk.
The most frightening one was when I went to Poland, 100 miles before reaching the polish border, my water temperature fluctuated badly. I stopped and noticed an almost empty water system. I had to make the decision whether to keep going to my racing destination (still 300 miles to go) or to go back home (900 miles to go). I stopped for 3 hrs to decide to go to the race session in Poland, putting coolant in the system about 1-2 quart every 100 miles. The car did the race and I came back home stopping every 100 miles to check water level and adding fluid.
Last time was this september 2009 for an abnormal
oil pressure value (20 PSI less than usual). I decided to stop the car before this could become worse or bad for this engine. I was coming back from a dragstrip and still 200 miles away from my home....So many thanks to my best friend who came to my help with a trailer.