Carter was 10 of 12 from the field as the Mavericks roared to a 43-21 halftime lead. Simmons connected on 5 of 9 from 3-point range for Nebraska-Omaha (4-12, 1-3 Summit).
Alex Welhouse contributed 10 points and 10 rebounds for the Mavericks.
Thomas Staton scored a career-high 23 points for the Kangaroos (4-10, 1-2), with 21 coming in the second half. Estan Tyler had 12 points and Nelson Kirksey scored 10 for Kansas City, which has lost eight straight Summit League games on the road dating to Dec. 1, 2011.