Ouch!!
Don't think it will do well at eventing - I don't think eventers want a horse prone to tripping like that, nor would they want a foal who has been doing that. Can you imagine the damage?? Poor thing ....
If you read the comments below, the foals were put on the slope to get some grass but this particular foal was curious to get down and so jumped into the arena. The foal was absolutely fine afterwards so fingers crossed he/she will be in the future. Foals will be foals I suppose.