Season 4 introduces the Robbie Reyes version of the Ghost Rider who drives a Dodge Charger instead of a motorcycle.
When Yo-Yo Rodriguez walks onto Zephyr One for her check-in, she greets Agent Davis by asking how his wife is doing. He answers, "Getting bigger every day," to which she scolds him, and he changes to, "Getting more beautiful every day." Maximilian Osinski, who plays Davis, is married to Dichen Lachman, who played Jiaying in Season 2 and was pregnant at the time.
The opening scene where Robbie Reyes' Charger is hit with an RPG, flips in the air, and lands on its wheels is a direct reference to All-New Ghost Rider #2.
S.H.I.E.L.D. is finally out of the shadows, and it has a new director because the public still thinks Coulson is dead.
The first reference to Life Model Decoys in the MCU was in The Avengers (2012) when Tony Stark attempted to avoid a video call from Agent Coulson, claiming to be the LMD for Tony Stark and reciting Stark's consultation hours. It didn't work.