Callejon notched a brace while goals from Nuri Sahin, Raphael Varane and Joselu ensured that Madrid brought the curtain down on a fruitful 2011 with a 7-1 aggregate win over the winnows as they progressed into the fifth round of the Copa del Rey.
Mourinho admitted that he relished watching how Callejon tormented Ponferradina.
"I already liked how Callejon played on his former team, which exploited his main characteristics very well," he said to the club's official website after the encounter.
"You never know how long it's going to take for a player to adapt to a new team and a new reality. Callejon has a strong and well rounded personality and he spent some years at Real Madrid. He is doing a good job."
"We're doing well. We're professional and my men are ambitious and hard working players. Our supporters are well aware of the characteristics of this group of footballers."
"Championships are won or lost by small details, as we clearly saw last year. This squad does its best every day and in every match."
"We would have a larger lead in another league championship. It isn't the case because there is another very good side here. We'll see if the job we're doing is enough at the end of the competition."
"It's hard for me to make individual assessments because my men play like a team. We had to win and give the wonderful people who came here tonight a good reason for them to leave their homes."
"Casado played his first game with the team. This is always a bit of a burden at the start, but later he had no problems and was calm, which is what we asked of him. What Sahin does is good to boost his own confidence; his goal and assist are good for his recovery process."
Mourinho added that he will continue to blood his young charges in matches deemed appropriate.
"Youth teamers will play again depending on the situation we're in. Today was perfect because we had no pressure and could be calm about it," he explained.
"I really looked forward to allowing Casado and Pacheco to make their first team debuts. Nacho and Joselu had already played for me. I have confidence in them if there's any problem."
The Portuguese also reserved special mention for minnows Ponferradina, an outfit who are currently plying their trade in Spain's third division.
"Ponferradina were an opponent of an inferior category, but a good team nonetheless," Mourinho commented.
"I heard the comments they made in the dressing room about being here to enjoy themselves. They left with the applause and respect of our crowd, and probably with more confidence for the future."
"They gave a correct performance and made a good impression. I believe they are capable of playing in the Second Division next year. I hope they do because they play well, they have a likeable nature and they gave us a great welcoming."
Madrid will now embark on their traditional winter sojourn in pole position in the La Liga standings, having amassed 40 points from a maximum 48, three ahead of second placed Barcelona.