Factual error: Aunt Petunia says that the chalice was first seen in the Stone Age, and sends Paul and Barry back to where Stonehenge is just being completed. However, the Stone Age actually ended in around 3300 BC. Stonehenge is believed to have been constructed in around 2500 BC, which was the Bronze Age.
Factual error: About 1/3 through the show, Greg has to talk to Marcia and asks Peter to leave. On the way out Peter stops to start recording on the tape recorder. He only pushes the play button. He would have had to push the red record and play button to record their conversation.
Factual error: Shannon asks Leah if she knows what happened to Tom Smith - she replies that Tom has gone to university, but in the previous series Tom was only in his first year of sixth form, and it takes at least two years in the sixth form to study for the A levels required for a university place.
Suggested correction: Although normally A-levels are taken after 2 years, it is possible (and often done) to study them in one year.
Factual error: As the robot bird approaches Earth, South America is the wrong way around.
Factual error: When we see the SPV escaping from the Culver Atomic Centre, it is night time. However, when we see Number 3 Tracking Vehicle, it has changed back to daytime.
Factual error: Ben Franklin's "electricity kite" experiment and the Declaration of Independence happened 24 years apart, not at the same time.