- The Southwest United States, Mexico, and most of Central America were under control of Spain until 1821, so how did the United Kingdom make the territories become part of West Britannia?
- The flags on the British ships during the ride of "Wrong-way Revere" were the current flag design, which was not used until 1801. The flags used in 1775 didn't have the St. Patrick's Cross of Ireland.
- Before Fry went on the head trip to 1775, he was wearing his Head Museum uniform. When he returned after fixing the timeline, he's in his normal clothes.
- During the alternate British future, Scruffy addresses Dr. Farnsworth as "My Lord". A duke should actually be addressed as "Your Grace" instead.