Quality control is a VERY important concern with company's producing scratch tickets.
You have to understand that depending on the particular press and game being run,tickets are being produced at the rate of 1+ million/hr. Some very large games can run for several days straight.
The quality(viscosity's) of the inks being used in vat's are checked hourly by the ink tech's.The security inks (covering numbers)are run thru the most rigorous/elaborated test to assure the ticket cannot be broken.
And yes to your question about misprints,they do happen.
Every once in a while large jackpots are won by more player's than the top prizes were structured for. Mistakes occur just due to the shear volume of tickets being produced yearly.
It is a big headache for the various lottery's globally to deal with as the integrety of the lottery games are at stake.You have to also understand how high tech this operation is.It is awesome to see the amount of computers that they use to produce these games from the start(designing tickets) to the final shipment.
I will answer your question concerning how top prizes are seperated.Each games that is printed produces extra prize amounts during production due to waste.
You have to understand the large amount of wasted tickets that are produced in the printing of these games.So after the game is finished running the large rolls of tickets are sent to a production line which slices and dices the tickets into saran wrapped packets.Ticket pack size vary according to $$ amount of the ticket.
Then they go into boxes and employess from security sort out the duplicate tickets so that the prize structure is balanced out according to the contract spec's for that individual game.The computer's know where to find the various winning tickets in these hundred's of boxes that are awaiting shipment.
The game is then shipped out(truck and plane) to the State/Country lottery corporation.The tickets do not become activated until scanned by the local ticket agent(store) or dispensed from a lottery machine.
Note;The lottery's HATE bad publicity concerning their business.They will go to geat lenghts to avoid it reaching the public's eye's/ears.............
Like I said earlier, quite an interestig job I had years ago.