Tyler Melville added 15 points for the Big Green (6-13, 2-3), as the trio made 20 of 31 field goals. Mitola was 4 of 5 and Melville 3 of 4 from 3-point range.
Dartmouth finished 7 of 15 from 3-point range to 3 of 20 for the Lions (9-10, 1-4).
A 14-2 Columbia run erased an 11-point Dartmouth second-half lead. John Daniels' dunk with 2:41 remaining put the Lions ahead for the last time, 54-52.
Mitola responded with a free throw, a layup and a 3-pointer for Dartmouth.
Maryland point guard Melo Trimble, considered a lock to leave the program before struggling in the second half last season, has withdrawn from the NBA draft and will return for his junior season.
Louisville's Chinanu Onuaku, who recently underwent a medical procedure to correct a heart rhythm issue detected during the combine, will keep his name in the NBA draft pool.
Andrew White III will return to the Nebraska men's basketball team next season after removing his name from the NBA draft.