Helen hands Goober a bowl of pretzels from the coffee table. In the wide shot he is holding the bowl and they are gone from the table. But a moment later, in the close up shot of Helen, Andy, Barney and Thelma Lou they are back on the table, then a moment later they are still in Goober's hands.
Andy asks Barney if he knows Lydia Crosswaith, but Andy would already know that Barney knows Lydia because Barney and Thelma Lou brought Lydia to Andy's house in Season 3.
When Goober and Lydia arrive at Helen's house, Andy introduces Lydia to everyone, including Thelma Lou. But in Barney Mends a Broken Heart (1962), when Thelma Lou and Barney tried to fix up Andy with Lydia, she was introduced to Andy as Thelma Lou's friend.
When Goober and Lydia go to Helen's house, stairs are seen behind Andy, Helen, Barney, and Thelma Lou. In the wide shots, it's evident the stairs don't go anywhere; they are blocked by plywood.