I remember some incidents from previous years, the air ambulance helicopter landed to air lift an injured rider away to Nobles hospital this scared a horse that jumped the fence onto the track, a rider hit the horse and was killed.
Another time only 2 years ago I think, a rider went down and a female marshal ran straight into the track to attend him right into the path of anther bike which killed her and the rider.
On Bruce Ansty's new record lap this year he made 2 mistakes, I think the first was at Creg-ne-bae where he missed the apex and went very wide very nearly hitting the bales on the pub wall on the outside then about 2 miles further down the mountain at signpost corner just after the 200mph+ fastest stretches he went straight on instead of turning right, the lap could have been a 133mph if he had not lost a few seconds on each of those turns. Signpost is a blind entry, you start braking before you go over the crest and see the turn, I have done the same and gone straight on there myself!! Maybe he was suffering with brake problems, it was his 6th lap! Coming down the mountain can boil the brakes of normal bikes, I found that out the scary way!!
Back in 1990 I built and tuned a bike that raced there and pit crewed for him, I wasn't the rider, it came in in 10th place in the newcomers race and finished both the lightweight and junior races. 1000+ miles of practice and racing in 2 weeks. Another bike I built for the same lad won a british championship.