However, third-placed Valencia missed the chance to close within a point of Barca when they slipped to a 1-0 defeat at home to Real Sociedad in Saturday's late kick-off.
Mallorca's Israel forward Tomer Hemed's superb glancing header gave the home side a shock lead over Madrid six minutes before the break at their Iberostar stadium but Real substitute Higuain levelled with a deflected strike 18 minutes from time.
Callejon grabbed the winner for the visitors in the 85th minute when he ran on to a loose ball and fired through a crowd of defenders past Hemed's international team-mate Dudu Aouate in the Mallorca goal to lift Real to 46 points from 18 matches.
"We were playing against a team with a great manager who were perfectly organised defensively," Mourinho told a news conference.
"They were very well prepared for this match," added the Portuguese. "They knew what to expect from us and they were very focused and did not make any mistakes."
Sevilla's bid to qualify for next season's Champions League suffered a setback when they followed up a three-match losing run with a 0-0 draw at home to Espanyol earlier on Saturday.
Struggling Granada's troubles deepened when they lost 2-1 at home to Rayo Vallecano and dropped to 16th.
