Cheyenne turns 21. When the series started in 2015 she was already 17, so she should be turning 22 in 2020.
When Mateo and Cheyenne are at the jewelry counter planning her birthday party, Mateo goes from leaning on the counter with his left elbow to standing upright with just his hands on the counter between shots.
When Glenn suggests that Sandra call Jerry about adopting Tony, she reaches into her left pants pocket as she starts to turn away from him. When she completes the turn, her phone is suddenly in her right hand and all the way up to her ear and she's already dialed.
When Amy and Jonah are discussing her taking the corporate job in her office, Jonah's arm goes from up on the desk to in his lap between shots.
The store is preparing for Easter, 2020, as though it were a usual year. Easter 2020 was April 9th, by which point Covid 19 lockdowns and safety protocols had been in place for weeks. Covid 19 would not come to the world of Superstore until the following season's premier.
When Jonah is rambling to Amy at the end of the episode and she cuts him off with a kiss, his mouth has already stopped moving a second or two before they kiss, but the dialogue continues up until their lips meet.
When Dina asks Jonah to restock the Icelandic yogurt, Jonah says he needs to check with Amy because he doesn't know if the previous day's scheduled shipment arrived. There would be no need to check with the store manager for that. It would be more sensible to check with the warehouse staff, who would have received and stored the shipment, or to just go and physically check to see if it was in the storage area.
Glenn tells Sandra that Tony was one of his original foster kids. It was established in Glenn's Kids (2017) that Glenn's older foster kids were, at that point, in their mid 20s. If Tony was one of his original foster kids, he'd be in his late 20s/early 30s in 2020 and thus aged well out of the foster care system.
Dina states that Jonah can't grow facial hair. Jonah grew a goatee while living in a FEMA camp, as seen in Grand Re-Opening (2017).