In the original movie Scott Hayden (Jeff Bridges) had seven silver spheres, which were the tools of his civilization. Every time he used one it disappeared. In the series, Paul Forrester (Robert Hays) has only one silver sphere, but this one doesn't disappear after one use.
Before the cancellation was announced, Robert Hays had been intending to leave the series. The second season premiere was planned to discover that the original Paul Forrester had survived his helicopter crash but suffering from amnesia. They would help Forrester get his memory back but would have required him to obtain a new body so Forrester could resume his own life.
In Starman (1984), the alien uses one hair from Scott Hayden in order to replicate his body. In the series, he uses blood from Paul Forrester.
Jeff Bridges was not offered to return in the role for the television series.