Mister Rogers' Neighborhood (1968)

S1E35 Red Monster Pt 5: There are no monsters

In episode number 0035, Mister Rogers visits and constructs a cozy tunnel using chairs and a blanket. Together with Chef Brockett, they create their own imaginative tunnels using items nearby. As the adventure unfolds, the citizens of the Neighborhood of Make-Believe come together, ultimately discovering that there are no red monsters hiding within their tunnels after all.