Will minor mistakes in my bachelor's thesis harm my future career as a researcher?

I have a perception that academicians are perfectionists and might persecute mistakes like this even when done unintentionally.

I am pleased to report that your perception is wrong! Academics are human beings who tend to be rather understanding of other human beings who, like themselves, occasionally make mistakes. In fact, if you browse other questions on this site that are tagged errors-erratum, you will find that mistakes happen quite often in academia, just as they do everywhere else.

One slightly ambiguous citation in a thesis is

• not going to bar you from doing research,
• not cause for taking away your degree, and
• not even cause for anyone to think poorly of you, assuming the rest of your work is good.

If it bothers you, put a corrected version of your thesis (and/or an erratum) on your personal website, just to set the record straight. (And realistically, if anyone happens to read your thesis in the future, they are far more likely to read your easily accessible online version than a printed copy in the library.)

It's bachelor's thesis. After it is approved, no-one will read it. Ever.

You're worrying too much. :)
It is uncommon not to have a minor mistake in a work of dozens of pages. It is very likely that you yourself will always be your worst critic. What will happen is:

• Most likely nobody beside yourself would notice the error
• If someone noticed, they would recognize it for the minor issue that it is

You've submitted your Bachelor's thesis and it was accepted. While it is fine to provide an updated version on your website as ff524 suggests, or even to have a look at previous projects sometimes, continually obsessing about past work will drain you. Do everything as good as you can, but once you've delivered it, it's time to shelve it and move on to new projects. ;)