They are telling people to continue to register today.
I assume that anyone who does register today may still be allowed to vote once they have checked the rules on this with regard to disenfranchisement due to technical glitches.
The electoral commission have said in a statement
it was "vital" everyone who wants to vote on 23 June is able to do so, with a "very significant increase" in online applications on Tuesday.
It added: "There will be many people who wanted to register to vote last night and were not able to.
"The registration deadline is set out in legislation and we have said to the government this morning they should consider options for introducing legislation as soon as possible that would extend the deadline.
"We would support such a change."
In essence they have admitted responsibility and liability.
Whether you agree with people leaving it late or not, the point is, unless those people are allowed the opportunity to vote the danger is that it could undermine the result - especially if it is close which it currently looks likely to be.
Both campaigns acknowledge this (though its worth saying that Vote Leave have also said 'We want everyone to have a chance to vote in this referendum, however our main concern is that the Electoral commission seems to be doing so little stop EU nationals from registering to vote in this referendum.", so don't be surprised by the vote being called into question anyway if Remain wins).
High turnout is a good thing is a sea of campaign shit.
What we really don't want now is a really close result tbh. I think the latest polls are saying that's what we are likely to get though so there might well be even more fall out from this further down the line.