Having re-fuelled commercial aircraft for the last 15 years,apart from venting tanks,I'm pleased to say I have had no incidents.Having said that,on one occasion at the airport I work at,we had an incident of the re-fuel coupling shearing which resulted in fueller and engineer running at 2 min mile pace!
There was also a case of the fueller driving off with the hose still connected! Fortunatly there was no major incident following this.
I have also seen a video of the ground connection being broken off by a baggage truck.The fuel must have shot 50' in the air!