Can internal splints for a septorhinoplasty be displaced inside nose after heavy sneezing?

Internal nasal splints are often attached to the septum with a suture. If you had a suture holding the splints in place, it is possible that the suture is slightly loose and that a vigorous sneeze may have caused one of the splints to move slightly further back into the nasal passage such that you may not be able to see it. If you have any concerns, you should call your surgeon's office such that your nose can be examined to determine the exact position of the splints.

Most surgeons suture the splints so they may shift slightly. Even if they weren't and moved its unlikely that anything bad has happened especially since your eight days out from surgery. By this time they have performed their function.  Best wishes.