Factual error: As the robot bird approaches Earth, South America is the wrong way around.
Factual error: Tori donates three pints of her blood. There is no way that the hospital would have done this in real life seeing as it takes about eight weeks before a person can actually donate blood again.
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: On the coach when the camera is on Miss Booth you can see out the window a road sign saying 5 miles to Hatfield and 15 miles to Stevenage. Grange Hill school is set in North London and they are on their way to the Field Trip on the Isle of Wight via Portsmouth ferry terminal - the coach is heading the wrong way as both these towns are in Hertfordshire, which is north of London, and Portsmouth is on the south coast of England.
Suggested correction: Correct in theory, but in a large, densely populated urban area it would make sense to go towards the faster motorways which, depending on where in North London, would be the Northbound M1 and M25 (the latter goes round Greater London) than go completely in the right direction which would take longer as it means going 10 miles through urban areas and thus take a lot longer.