If you comment on a situation, or make a comment about it, you give your opinion on it. You may express a careful thought, or you may just say a few words.

1. He knew his father expected him to comment on the meal.
2. “It’s going to be pretty cold if you have to stay there all night,” he commented.
3. “I’ll believe it when I see it,” was Mrs Pringle’s comment.

If you mention something, you say it, but you do not spend very long talking about it. You have usually not been discussing it before.

4. She casually mentioned: “I thought I had something of interest for you.”
5. Johnny mentioned that he might be in New York right after the holidays.

If you remark on something, or make a remark about it, you say what you think or have noticed about it, often in a casual or informal way.

6. Visitors generally remark on how well the children look.
7. Mr Nixon hastened to remark that he was not against television.
8. Gerald Sutton’s first remark was: ‘Your pals have found you.’