Original Sentence: The report, which was submitted late because of unforeseen circumstances, showed several errors that needed to be fixed urgently.

Improved Sentence: The report, delayed due to unforeseen circumstances, contained several errors that required immediate correction.

Explanation of Improvements:

1. Conciseness: “Submitted late because of” is replaced with “delayed due to,” which is more concise and formal.
2. Clarity: “Needed to be fixed urgently” is rephrased to “required immediate correction,” aligning with professional and formal tone standards.
3. Flow: The revised sentence eliminates redundancy and improves readability while retaining the original meaning.