The much-loved City on a Hill star was recording one of his Monday Blues videos during which he makes musical suggestions for his social media followers.
But the upbeat clip was eclipsed by the scary detail which could be seen behind Kevin.
WATCH: Kevin Bacon and Kyra Sedwick perform adorable duet on anniversary
The actor left many fans "disturbed" and "creeped out" because he'd placed a piece of movie memorabilia on the bookshelf - and it was pretty scary.
The item in question was the Hollow Man mask he wore in the horror film of the same name.
Kevin's fans commented on the prosthetic and wrote: "The HM mask staring into my soul," and said, "that invisible man mask is creeping me out".
Many of Kevin's fans couldn't get past the scary Hollow Man mask in the background
Another added: "I’m more disturbed by the Michael Myers type mask in the background."
Kevin responded to some of the messages with a spooky eyes emoji, suggesting he'd placed the mask there on purpose.
Despite the unexpected detail, the majority of Kevin's fans thanked him for the hits he suggested and told him how much they adored his videos.
Kyra and Kevin say they "got lucky" to have found one another
He regularly delights them with insight into his home life with Kyra - who he has been married to since 1988.
Kevin recently had Kyra all excited over a bowl of his vegetarian bolognese. He documented the meal on Instagram and fans flocked to tell him what an adorable husband he is.
"Good job Kevin! Your wife is happy!" wrote one, while another added: "You are so kind to cook for her." A third commented: "Such a sweet husband!"
The couple have two grown children together and when Kyra was asked by The Post why their marriage has stood the test of Hollywood time, she admitted: "Honestly, we just got lucky, there's no secret, we just got so lucky when we were so young."
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