Live Aid in Philadelphia ended around 11pm. Spectators would have been exiting the stadium at night.
The cast attends Live Aid, which occurred on July 13, 1985, but in the voice over following the credits Adam says the episode takes place on October 5th 1980 something.
In the opening scene, when Barry is trying to explain to his dad the need to go to Live Aid, his red and black shirt appear wet, as if he had spilled water during a drink. One quick cutaway later the same shirt does not have these water stains.
According to Adam's opening voiceover, this episode takes place on "October 5, 1980-something," yet Live Aid took place on July 13, 1985. Not only is the date incorrect, but the children wouldn't even be in school during Live Aid, as they would be on summer break.
Live Aid took place in 1985, so we know that's when this episode is set, yet Adam quotes Dana Carvey's SNL character The Church Lady. The Church Lady didn't make her first appearance on SNL until 1986, the year after Live Aid.
In the parking lot at Live Aid, the logo of the PAC 12 conference is visible on a sign in the background. This is a college athletic conference whose member schools are nowhere near Philadelphia, and did not expand to 12 schools until 2011.
Erica gives her fake boyfriend the name Jordan Wahlberg, and Adam accuses her of just combining names from two guys from New Kids On the Block. This episode takes place when Live Aid happened in July 1985. Even though NKOTB had formed in 1984, the group did not become household names in the pop music scene until 1989-90, well after Live Aid.
When Beverly and Murray are stuck in traffic outside the Live Aid concert, you can clearly see the Pac-12 (non-football) logo in the background on a gate. The Pac-12 formed in 2011 when the University of Colorado and the University of Utah joined the former Pac-10 Conference. In terms of geography, all member schools of the conference are in the pacific, mountain, and southwest regions of the Contiguous United States--with the furthest east member being the University of Colorado in Boulder, Colorado.