I didn’t see the show, but a few general pointers…
Several other religions besides Catholicism use a communion wafer during their services, most often when practicing a sacrament called “communion”. Likewise “nuns”, or women in a religious order. So technically, just having a nun and a wafer doesn’t necessarily make it Catholic.
So, if the setting was not clearly spelled out as being a Catholic communion sacrament, then there might be more leeway as to what the nun should’ve done.
As far as the Catholic communion sacrament - the wafers themselves come in a plastic tub a few thousand at a time (former altar boy here). They are not holy, not blessed, nothing.
During the Mass a priest blesses the wafer (simplified version of events), and by doing so the wafer is technically transmuted into the Body of Christ. (Believe what you want, but some people believe this actually happens.)
So… Peggy didn’t drop an unblessed wafer on the floor, she dropped a little piece of Jesus. Quite a difference. (Again, you don’t have to believe this, but some people do.)
In Catholicism only a priest can bless the wafer and change it into the Body of Christ, but after that practically anyone can pass them out (within reason). They are called “Eucharistic Ministers” and are typically people who are serious Catholics, take some classes, go on a religious retreat, get a blessing from a priest, and there they are. Everyone has the same obligation when passing out the Body, so a priest wouldn’t be required to do anything different than a nun, or a eucharistic minister, or the Pope for that matter (“Hey John Paul! You fumbled the Lord!!!”).