「記入漏れあり」は英語で You forgot to fill out/fill in some sections もしくは some sections were (left) blank/There were some blank sectionsになると思います。
Fill out / Fill in (a document/ a form) – 記入する
There were some sections that you forgot to fill in – 記入し忘れた箇所あったよ。
You missed some sections. 見落とした箇所・ところあったよ。
There were some blank sections- 空欄のところあったよ。