I failed physics my freshman year (and got a 50 exactly when I took it over again in second year! ouch!). I expected it to come up in interviews, but it really didn't seem like an issue.
If you are worried, one thing you can do is show that this does not reflect on your abilities to handle grad school. For instance-- if physics was the only math/hard science I ever took, a professor looking at my transcript might assume that I wouldn't have the math skills to succeed in graduate school. In order to ensure it wouldn't be a problem, I made sure to do VERY well on in my stats courses, to get a good score on the quantitative portion of the GRE, and to do well in upper year chemistry and biology courses.
If the grade is in an English course, you should do everything possible to show that this is one grade and does not reflect on your writing abilities. Do well in any other English and Lit courses you take. Try to score well on the verbal and analytic writing sections of the GRE. Make sure that your personal statement is very well-written. If you do all that, that one grade will be just that-- one grade-- and shouldn't hurt your application.
Hope that helps. 🙂