It totally depends on the competitiveness and the regulations within the admission committee.
Usually, there are several possible criteria (not counting recommendation letters, statement of intent, etc) regarding student's grades that are taking into consideration:
- Overall GPA
- GPA for a specific group of subjects that are essential for a graduate program (say, GPA for STEM classes)
- Grades in individual courses.
Grades for individual courses are usually considered by a potential advisor who looks deeply into the students he wants to add to his group. In that case, the situation will depend on the pool of potential candidates to his group and him believing that more advanced math classes outweigh Calculus I (@GEdgar) - which is a very reasonable assumption.
The priorities of criteria 1-3 can be shuffled depending on the admission process; however, there is nothing that you can do about your past grades. Moreover, I would lean towards the opinion that your situation is totally fine – a lot of students have bad periods during their degrees. In your case, it is limited to only one subject Calculus I. Nothing to worry about.
One thing that you still might consider is to reflect on this fact in your statement of intent (or some other document in the application package). You can view this situation from a very positive angle and highlight your best qualities. But in your situation, I would say, even this is unnecessary.