The Technicolor Time Machine

This is a light comedy novel with no pretension to literature or seriousness, but it's a mildly entertaining yarn that passes the time well enough.

A film studio in urgent need of a successful film meets a nutty professor with a homemade time machine, and decides to make a film about the Vikings discovering America. The team goes back in time, recruits some real Vikings, has many amusing problems, and eventually delivers the film.

Although the story is primarily a comedy, Harrison did his research, and threw in some historical information and some scraps of Old Norse. There are also some time-travel complications to keep sf fans happy.

It was first published in 1967, so the parts of the story set in the present are a bit dated by now; but much of the story takes place around the year 1000, in the time of the Vikings.