There is a clear nod here to 1939′s The Wizard of Oz which also started off in black and white and when Dorothy reached Oz, the film became colour. In the 1930′s Technicolour technology was new and The Wizard of Oz is applauded for it’s technical achievement. The storytelling device in the original film is to show the contrast between the two worlds. In the original text, Kansas is described as grey and lifeless whilst Oz, being over the rainbow, is colourful. There is also an element of reality (black and white) versus fantasy (colour) between the two worlds.