Looking for a TV show?

I'm thinking this is an episode of the outer limits. But here is a run down of the show, A man looks at a full length mirror. He sees a speck on the mirror and he tries to clean it off. He keeps flaking it away and discovers another world through the mirror. He goes through it to a prehistoric land. Latter Some people follow him through the mirror. Something happens and they begin to chase him. He comes back through the mirror into the real world but paints over the mirror leaving the other people trapped in the other world. Do you happen to know what TV show is this and what episode? Does any one know what the name of this exact episode is? And if its not the outer limits, does any one know what show it is? Thanks.