Twitter, after laying off roughly half the company on Friday following Elon Musk’s $44 billion acquisition, is now reaching out to dozens of employees who lost their jobs and asking them to return.

Some of those who are being asked to return were laid off by mistake, according to two people familiar with the moves. Others were let go before management realized that their work and experience may be necessary to build the new features Musk envisions, the people said, asking not to be identified discussing private information.

Twitter cut close to 3,700 people last week via email as a way to trim costs following Musk’s acquisition, which closed in late October. Many employees learned they lost their job after their access to companywide systems, like email and Slack, was suddenly suspended. The requests for employees to return demonstrate how rushed and chaotic the process was.