C.B. is bumped by Erica in the teacher's lounge and he spills his coffee all over his shirt and tie. When we see him again a few moments later during the same scene, his shirt and tie are completely dry.
The high-school reunion involves many characters from The Goldbergs who were in lower grades when Lainey and Erica graduated from high school; therefore, these students wouldn't be invited to this reunion, because high-school reunions are only for a given class year, especially the first reunion of a class, which this seems to be.
Specifically, Carla and Johnny were in Barry Goldberg's class (a year behind Erica's), and Dan was in Adam Goldberg's class (three years behind Erica's).
Specifically, Carla and Johnny were in Barry Goldberg's class (a year behind Erica's), and Dan was in Adam Goldberg's class (three years behind Erica's).
According to the opening voiceover, this episode takes place on March 13. When former student and current Philadelphia Philly Rubén Amaro, Jr., visits, Principal Glascott says that he saw Amaro's "big game" the previous week. Baseball season doesn't start until April.