A book by Harry Harrison, published in 1967.
I recently read this book again (it was the book that originally started my long but also short SF book appreciation), having had somewhat enough of Harrison's "humorous" works like Bill the Galactic Hero series that were more than fun but lacked some good foundation and lasting values. Now, The Technicolor Time Machine is a good example of a funny SF book that also has so-called serious SF elements and a plot that is worthwhile.
The book is about a movie company that is drawing its last breaths. The studio has, of course, only been producing low-selling crap, and soon it's time to close the doors for good.
Now, a director called Barney Hendrickson wants to get a permission from his boss to make yet another movie - because that has a very good chance of saving the company - even when the creditors will soon be knocking on the door!
Barney tells (and demonstrates) his boss a new invention from professor Hewitt. Hewitt calls this thing a vremeatron - and the demonstration indeed makes the boss convinced. Vremeatron is a fully working time machine. The potential!
The invention is about to revolutionarise low-budget filmmaking! There's no need to to build expensive sets, they can go right there where historical things happened and get the cameras rolling! And since they can return to more or less any point of time, the time passes slowly in the studios, and they'll be able to make movie in a record-breaking time...
Using the time machine, they explore the ancient world, meet a viking called Ottar, send a scriptwriter to prehistoric era to make a script for the movie called "Viking Columbus" - and once that's done, it's time to film the departure, arrival to the famed Vinland, and the colony's first moments... but the filming doesn't always work as intended!
I liked the book a lot; It dealt with some interesting time travel paradoxes, it had a lot of humor from the not-too-well-mannered vikings, and of course the subtle impact of time travel was right there... A very nice little book on complexities of B-movie studios and production, and disruption of natural causality.