Originally, all surviving cast members of the TV show were meant to have cameo appearances. Mark Goddard, the original Major Don West, plays the General. June Lockhart, the original Maureen Robinson, plays Will Robinson's principal. Marta Kristen and Angela Cartwright, the original Robinson girls, play reporters. Ironically, Bill Mumy and Jonathan Harris, the two actors most supportive of the idea of a new movie (as well as the two most popular characters on the show), did not appear in it. Mumy wanted to play the older Will Robinson but the director thought it would be too distracting from the plot to have the original Will play the older Will. Harris was to have played the man who hired, then betrayed, Dr. Smith. In an interview for "TV Guide" prior to the film's release, it was mentioned that Jonathan Harris bluntly stated, "I will have you know I have never done a walk-on or bit part in my life! And I do not intend to start." He announced that if he could not play his own role in the movie, he wanted nothing to do with it. He did return as Dr. Smith in a one-hour TV special Lost in Space Forever (1998).
Ib Melchior was given screen credit and worked as special advisor to Mark W. Koch in Lost in Space (1998) because he was the creator of the original "Space Family Robinson" (1960) - a screenplay, which became Irwin Allen's Lost in Space (1965) TV series. Melchior was never credited for the creation, until the details were exposed in Ed Shifres' "Space Family Robinson: The True Story" (Windsor House - 1996) and re-published as "Lost in Space: The True Story" (Windsor House - 1998). The book was extremely controversial and earned Melchior a monetary settlement and recognition as the creator of what became Lost in Space. The book was critically acclaimed with excellent reviews from Hollywood notable writers.
Despite opening in theaters on April 3, Lost in Space (1998) was the first new film of 1998 to open at #1 at the box office. This was due to the incredible 15-week reign of Titanic (1997) at the top spot, which began in late December. Since it finally knocked "Titanic" out of the #1 spot on the box office charts, for a short time after its release the movie was given the nickname "The Iceberg".
In the script the ship with the spiders doesn't have a name while in the movie it is called The Proteus. You could also notice this later on when Older Will talks about how the spiders survived by watching his lips move.
The trivia item below may give away important plot points.
According to the screen writer, if this movie did receive a sequel it would have been about the Robinson Family making it to Alpha Prime. However they'll discover that Alpha Prime is already populated with humans because they previously went through a worm hole in the first movie that sends them into the future. Along with a sub-plot with Judy Robinson creating a cure for Dr. Smith to prevent the spider infection from turning him into Spider Smith and Penny ending up receiving the same color changing abilities as Blawp has.