Yes, it happens. As above, on a DCL excursion you are safe--they will wait for you.
On a non-DCL excursion, we always plan on being back on board at least an hour before "all aboard;" this covers me if I somehow screwed up the local time calculations. In addition, take the Navigator with you. Each port day, there is an item in the Navigator of the "Ship's Agent." This is the number you would use in the event of an emergency to get a message to the ship, etc.
Say...worst case....you went off on your own on an island and ended up in a medical facility. Whether you will be sailing with the Magic that evening or not, you'd better let them know who you are and where you are. You'll need help getting your passports and other stuff off the ship if you're going to need to stay there, etc. The ship's agent is your starting place for all your contacts.
On the EBTA DCL left a couple behind and they had a small child on board. A CM had to stay with the child until the next day when the parents caught up with the ship. So I suggest you be on time if not early!
That's why I think it's worth paying the extra money for DCL sponsored excursions. It's like insurance, only better--you KNOW that you're going to get back on that ship!if you are on a DISNEY sponsored excursion they wait.
If the ship stays at the port later than their scheduled time DCL is charged hefty fines as well.
That's what I heard too. The CMs said it was something like $10,000 per extra minute of unscheduled docking time. At that point, we were all watching a couple running to the ship as we pulled away. The ship did return to the dock which the CM said was unusual.
That's why I think it's worth paying the extra money for DCL sponsored excursions. It's like insurance, only better--you KNOW that you're going to get back on that ship!
Beth
West bound transatlantic, leaving Canary Islands for six days at sea - someone missed the ship.
My DD boarded about 45 minutes before "all aboard" time and got to overhear all in the boarding area. The people sailing with the person were given the choice of continuing on the cruise, or packing all their stuff and getting off. The crew went to pack the belongings of the missing person and those who decided to leave. Shortly before the ship sailed they flew into a cab and headed out - probably to try to find the person.
We watched from deck 10 and they never showed up before sailing. We sailed no more than a half hour after the scheduled time. I am sure the docking fees were hefty.