At one point, Buddy tells Sally that they've been writing together five years. Yet from flashback episodes, we know that they were a writing team before Rob was hired as head writer by Alan Brady, which was also before the Petries' son Richie was born, detailed in another episode set after Rob has been working with them for some time. Larry Mathews, who played Richie Petrie, was 6 the year this episode was filmed, so Buddy and Sally have clearly been a writing team longer than five years.
A big log disappears from the fireplace just before the fire starts and re-appears in the next scene.
Laura comes out of the cabin bedroom to get her make-up case but goes back into the bedroom without it as it is still sitting on table by the sofa.
When Rob is getting ready to share the sleeper sofa with Buddy, Laura makes a remark about Rob stealing the covers. Rob, in reference to Sally sharing a bed with Laura, makes a remark about Laura stealing a pillow. The only way they would know these things about each other is if they shared the same bed. But we know they don't, because the show followed the ridiculous "married couples have to sleep in separate beds" rule enforced by the networks.