This story made me laugh.
At least it isn't just the UK transport system that sometimes goes awry. Imagine getting on your train, to Milan, and it's an overnight train, so you settle down to sleep. You have no reason to expect to wake up anywhere other than Milan.
Apparently the train was one of those that gets split at a certain point. The two parts were sent in the wrong directions. The part that should have been going to Zurich was re-routed after the mistake was recognised, so WHY did no-one realise the other part was going to the wrong destination as well?
I think it is ironic that the train was named after a famous surrealist, Salvador Dali. I would guess even he might have thought heading for Milan and ending up in Zurich a little too hard to swallow.
My sympathies are with the travellers, but on the plus side, they may never have been to Zurich before.