Hey army to civilian,
You don't have to worry too much about it. The school understands that typos can be made even after thorough reviews. As long as there aren't too many typos, you should be fine. Schools don't reject good candidates for one typo, they will be more interested in the story you are telling them and your overall profile . I suggest using the chrome add-on 'Grammarly' which is free of cost and catches such errors.
To catch such errors we at MiM-Essay have created a final checklist, that may help in removing such errors and improving the overall quality of the essay.
You can check it out here
https://www.mim-essay.com/mim-essay-help.html
Hope this resolves your query.