All the cool kids had surprise foals this year. 
I understand that it is possible to miss some of the signs of pregnancy. However, gee she’s fat and we can’t get the weight off her, after she’s been in a field with very recently gelded colts and she’s running slowly compared with her previous form?
“The filly, Beautyatitsbest, is an unraced daughter of Gio Ponti who had just breezed a slow three furlongs in 40 seconds on May 26. Two days later, she delivered what Reed said is a healthy colt – much to his surprise”. Yikes 
Whoops. That’s a pretty heinous mistake.
Without all the witnessing etc, what can they do with the foal? Obviously they’ll be able to tell who is the sire, but can the foal be registered with the Jockey Club?
When you don’t even think or realize pregnancy is a possibility, it’s not too hard to fail to put two and two together. It’s not like Reed and the people caring for her in training knew she was turned out with recently gelded colts! My horse, who they knew was bred earlier that year, came advertised as a very easy keeper. 
@endlessclimb There shouldn’t be any issue registering the foal.
I would think they would be able to register, assuming the gelded colt is also registered with DNA on file. It she was pastured with them, I would assume it’s live cover. Not sure if there are rules I don’t know about obviously, but in this case I would think they could.
There are no rules about “witnessing” or anything like that. Some breeders run pasture stallions with herds of mares. It just needs to be LC and no one will challenge you for proof of that unless you give them a reason to be challenged.
Depending how quickly the owner reported the gelding of the colt, there might be a moment of pushback with regard to the dates, but I doubt it.
While a filly getting bred by a gelding isn’t common, “oops” matings happen often enough with thoroughbreds. You have tons of colts stabled alongside tons of fillies. Accidents happen.
