When I joined a large well-known tech company, their background check red flagged my claim of having previously worked in the research division of an automotive

When I joined a large well-known tech company, their background check red flagged my claim of having previously worked in the research division of an automotive company. Luckily, I happened to know the tech company's CTO from when we both worked there! I don't know if the HR rep actually confirmed it with him when I offered him up as a reference.