When Garrett is talking to Jonah about dating Amy, Garrett is starring straight ahead but when the camera angle changes he is suddenly looking directly at Jonah, to his right.
When Glenn is telling Bo to calm down after losing the stroller race game, Bo puts his hands on his hips, but when the camera angle changes, Bo's hands are suddenly down by his sides.
Jerusha thanks her Uber driver for getting her to the store from Ponderosa so quickly. There were no Ponderosa restaurants in St. Louis, MO, where the show is set, in 2018. The nearest in operation at the time was over 50 miles away in Washington, MO.
Sandra says that it was October and thus there weren't a lot of options for a Christmas tree. Big box stores stock for Christmas in October. There should have been as many options for trees as there would be in November or December, if not more.
When Jonah finds Amy test-shaking a high chair, he tells her she's going to make "such a great mom." Amy already has a child, and thus has been a mom for over 14 years.
When Dina says she wants a Christmas card photo to blow her ugly sister Denise's out of the water, Sandra asks if Denise is the one with restless leg syndrome. Dina only has one sister. Sandra is supposed to have highly superior autobiographical memory.
When discussing his vision of Dina's post-apocalyptic Christmas card photo, Mateo posits the hypothetical of "what if the Grinch had succeeded in conquering Whoville?" The Grinch was never trying to conquer Whoville, he was just trying to stop the Whos who lived there from celebrating Christmas.