Many viewers questioned what the Irish bombers would have been doing in an English registered car.
But what was even wider of the mark was the fact that the two men represented as being in the car had actually been arrested two hours BEFORE the bomb went off.
Thomas McMahon who was said to have planted the bomb and his alleged accomplice Francis McGirl were being questioned in Granard Garda Station in Roscommon about a stolen car when news of the bombing came through. So obviously they couldn't have been in two places at once.
McMahon was later convicted of the murders but McGirl was acquitted - though his death in 1995 in a farm accident was deemed suspicious by republicans.
Some fans of The Crown have suggested that the two men in the car could have been other IRA terrorists who triggered the radio-controlled bomb. But The Crown's credits give the lie to that theory because they include the names of McMahon and McGirl and the actors who played them. Other mistakes were lurking in The Crown however. During Mountbatten's funeral as a choir sang Jerusalem, an actor's voice could be heard reading out an IRA statement admitting responsibility for the murders and gloating over the Earl's death.
The producers cut to archive footage to emphasis the import of the statement. However, the pictures showed the UDA on the march not the IRA and later on there were images of protesters holding aloft banners with the names of republican hunger strikers who died TWO YEARS after Mullaghmore.
Erroneous footage from a republican march two years later
What was also noticeable in The Crown was that there was only the briefest mention of the IRA's bombing at Warrenpoint which killed 18 of Her Majesty's forces on the same day as the Mountbatten atrocity.
And I couldn't help wondering why the credits didn't make any reference to the actor who portrayed Enniskillen boat boy Paul Maxwell who was killed at Mullaghmore.
But it wasn't just the Irish storylines with which The Crown took liberties. The programme makers were slated for completely inventing a passage of the drama in which Lord Mountbatten wrote a letter from Classiebawn Castle at Mullaghmore just before he died to Prince Charles attacking him for his liaison with Camilla Parker Bowles.
No better man than journalist Richard Kay who became a royal correspondent after his time in Belfast working for the Daily Mail filled a whole page with withering criticism of The Crown's interpretation of the Princess Diana/Prince Charles/Camilla love triangle. Maybe the success of earlier seasons in The Crown could be attributed to the fact that viewers had only scant knowledge of the reality of what they were seeing on the box from the 50s and 60s. But many people watching Season Four have clear recollections of what went on - and what came off - during Charles' dalliances with the ladies in his life. And a lot of it simply didn't ring true.
As for the acting I reckon Gillian Anderson - aka Det Supt Stella Gibson - took a right old Fall from grace with her portrayal of Maggie Thatcher. She definitely looked the part and her impersonation of the late PM's speaking voice could have come straight out of Spitting Image but the faltering delivery got right up my nose, though it has to be said the real Iron Lady made me spit feathers too.