"Potential" can be used as a noun or an adjective. As a noun, it is hard to consider it a count noun. If "potential" is being used as a mass noun, no article is required.
I gave her water
I gave her a book
If, however, "potential" is being used as an adjective, whether a determiner is needed depends on the noun being modified and its number.
We have potential oppurtunity to ...
We have a potential oppurtunity to ...
is correct, as is
We have potential opportinities to ...
In the sentence quoted, it is possible to read "potential" as a mass noun or as an adjective modifying an implied plural count noun such as "opportunities." In both those cases, the lack of an article is correct.
Notice that your site suggested that you consider adding an article. I would not add one, but I certainly would not say that adding one is wrong.
EDIT: I see that a different answer has suggested that no article is preferable, but if an article is added, only the definite article is acceptable. I am not sure I quite agree with that. I do agree that the definite article would be far more common. For example,
There is a potential opportunity for improvement
is obviously fine. I think that could be condensed into
There is a potential for improvement.
I do not like it, but a native speaker might say it. As indicated above, I prefer either
There is potential for improvement
There is a potential opportinity for improvement.