Harry Harrison 
Technicolor Time Machine [EPUB ebook] 

L M Greenspan, the head of ailing Climactic Studios, gave producer, Barney Hendrickson, five days to get a major movie in the can — and Climactic out of it.Impossible?Not with Professor Hewett’s miraculous presto chango time machine, the answer to Hollywood producer’s prayer.Nipping back to AD 1, 000 with a whole film crew and two glam stars, Barney sets out to prove that the Vikings discovered America five hundred years before Columbus — and to film the event in glorious Technicolour. But it’s not as easy as it sounds, as they realise when history lets them down and their Viking Columbus fails to show up in the New World.