When Barney first draws his Hot/Crazy scale, he places two Xs in the blank chart. Moments later, when he draws a line connecting them to the origin, the Xs are in different positions AND have rotated to match the angle of the line.
At the end of the episode there is a flash-forward to a college reunion held in 2020. This reunion was in person and not via Zoom, but could still have occurred in 2020 if it was in January or February.
When Ted first described meeting Marshall he said that he walked into the room and saw his roommate (Marshall) with his feet on the wall. But in this episode when Ted first walks into the room and meets Marshall, Marshall is standing up spraying deodorant and hiding a joint.
When Barney uses his Hot/Crazy graph with the example of a girl he dated, he uses the graph wrong. He said that she loses 10 pounds which indicates she's got hotter but instead he draws a line which actually said she's gotten less crazy, and the following line should be that she got crazier but instead he draws a line that said she's getting hotter and crazier, and finally he again draws a line that makes the girl less crazy instead of hotter.