I’m not sure how likely this is. When all the major players in a tragedy are dead, it would take an extra bit of effort to get a lot of mischance happening.
Who’s going to be committing these errors?
Osric? Horatio himself?
I mean, if I had to choose someone to kick off some mischance, Osric would be the likeliest candidate – especially if it were some gossip related mischance. But Osric is also a witness – so, he knows, at least, the end of this story.
But a bunch of plots and errors really need someone to be putting them forth and there aren’t many possibilities left alive at this point.