Frankly, it would be cheaper -- and take less time -- to simply paint a hammer with the words "Families are important" and just hit yourself repeatedly until you get it: "Families are important." That's how I felt watching Simon Wells' animated adventure comedy in which a boy goes to Mars to get his mom back. (Don't ask: The plot is so stupid.) The 3-D effects of this Disney outing make Mars look pretty cool; they also make the fem-bot-ish girl-Martians' huge butts stick out real good. (The boy-Martians are inexplicably wild, grunting, dancing Rastafarian-monkey hybrids.) The sketchy plot equaled lots of frantic action, frequently interrupted with reminders that "Families are important." Laughs were few (I counted two, plus one during the credits), and jokes rooted in the pop culture of the 1960s and 1980s couldn't have meant much to today's kids, who don't even remember the 1990s. Starts Fri., March 11.