The Technicolor Time Machine

This is a light novel with no pretension to literature or seriousness, but it's an entertaining yarn all the way along, and I enjoy reading it; although I reread it quite rarely.

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 readers happy.