Broken Bow didn't actually have a crossover from another series as such the actor who appeared was from the film Star Trek: First Contact. James Cromwell's appearance as Zefram Cochrane was purely a cameo more than anything else and the character didn't do anything or really affect anything in this episode. There is simply so much going on in this episode that the cameo gets lost in the mix. Broken Bow did hold up a lot of promise for Enterprise but it wasn't at all what the producers wanted to make as the original premise for the entire first season was effectively covered in this episode. Season one would have seen the construction of the Enterprise and returning their Klingon to the homeworld. Arguably it would have made for a much better season one. Admittedly the producers by this point were stuck with tradition. It was expected for there to be some sort of crossover as Broken Bow was a pilot of a new Star Trek series. The only characters who appeared in an earlier setting than Enterprise (other than the various 20th and 21st century time travel episodes) were those in Star Trek: First Contact and Cochrane was the obvious route.
