Tom Mason refers to "the Scots against the British at Stirling Bridge" as an example of a weaker force defeating a stronger one. He should have said the Scots against the English as British refers collectively to the Scots, English, and Welsh (and for some Northern Irish). It seems an odd mistake for a history professor.
Tom Mason uses historical examples of battles. He refers to the Battle of Stirling Bridge (1297) as the Scottish against the British. It was actually the Scottish and against the English - the formation of Great Britain and the cultural identity of being 'British' only existed from the 18th Century. The character is actually a history professor so shouldn't make this sort of mistake.
Porter says he's sending one group of people to Marblehead and another along Route 3 to Revere in order to scatter them from skitter aerial recon. Revere is on the way to Marblehead from Boston, and neither US Route 3 nor State Route 3 go anywhere near Revere.