Online voting - what could go wrong?

Specifically, the voting for a second referendum for England's exit from the EU - from Breitbart:

3M+ ‘Remain’ Petition Uses ‘Script’ To ‘Fake’ Signatures: 25,000 From North Korea, 2,800 From Uninhabitable Antarctic
Questions are being raised as to the true number of UK citizens signing a petition to urge another European Union membership referendum as evidence emerged that activists are encouraging foreign signatories. Some critics claim that a “bot” or “script” is being used to automatically generate names and signatories.

As of early Sunday afternoon, over 3.1 million signatures had been registered on the petition named: “EU Referendum Rules triggering a 2nd EU Referendum” which calls for the “Government to implement a rule that if the remain or leave vote is less than 60% based a turnout less than 75% there should be another referendum.”

But an analysis of the data on the petition shows that at least 6 per cent of the signatories, or nearly 200,000 are from foreign countries. While foreign-based UK nationals are allowed to sign UK petitions, some believe that many of these are fraudulent given that Remain activists are handing out post codes online in order to elicit more signatures from abroad.

Some numbers:

As of Sunday afternoon, around 41,118 signatories have come from Vatican City, 11,717 from the United States, and curiously, 24,855 from North Korea.

At least 19,000 signatures have come from France, and 2,735 from British Antarctic Territory, which has a population of just 250 people.

And this:

Turnout in the 2015 General Election was 36,185 in the Cities of London and Westminster constituency. Yet over 40,000 are claimed to have signed the Remain petition from that constituency in the past few days. That would mean that more than every single person that voted in 2015 has signed the petition, including all voters from the UK Independence Party and the Conservative Party, the former of which is overwhelmingly Eurosceptic, and the latter of which is split in half over the issue.

The numbers are patently false so the referendum needs to be nullified. You want to play politics? Don't cheat.