Continuity mistake: About 3/4 through the film, which is supposedly set in the 1900s, there's an exterior shot of Jenny Agutter (as Roberta) talking to William Mervyn (as "the old gentleman"). Over Mervyn's shoulder can be seen a white delivery van driving rather fast along a road on the other side of the valley from where the filming took place (this is very obvious in the wide-screen version but less noticeable in the pan-and-scan TV version).
Continuity mistake: When the Grammar School boys are on the paper chase they run through a railway tunnel. The Railway Children go to the opposite end to see the grammar school boys come out, as they are waiting for the final boy to come through, the paper that is thrown on the ground for the boys to chase appears then disappears several times.
Peter Waterbury: I'm very sorry I haven't got tuppence to give you like father does.
Albert Perks: Hey just stop that please, I wasn't thinking about no tuppence. I just came to say sorry your mama wasn't so well and to ask how she finds herself this evening. And I brought you some sweet briar, very sweet. Tuppence indeed.