Continuity mistake: When Spidey first interrupts the criminals on the ferry, there are 2 motorbikes behind him on the left. When he throws one of the bad guys around with a web, the bikes have moved to the right, along with the yellow markings they were on, showing the shot's been flipped. They then move back.
Continuity mistake: In Peter's personal vlog of the airport battle from Civil War, he jumps in, grabs Cap's shield and immediately says "hey everyone." However, in Civil War he jumps in and grabs the shield without saying anything, Tony says "nice job, kid", there's a longer chat about the suit, and only later does Spider-Man say "hey everyone."
Continuity mistake: After Peter gets the text from Happy about meeting at the bathroom, Michelle asks, "What are you hiding, Peter?" and just as she says, "I'm just kidding I don't care," Peter's holding his cell phone up in his left hand, but next shot he's holding the cell phone up in his right hand.Super Grover
Continuity mistake: When Ant-Man goes giant during the airport fight in Civil War, Peter is out in the airfield and reacts with a surprised "holy shit!" His video diary in Homecoming instead shows Peter hiding away from the action, and he reacts to the moment with a more subdued "aw crap, he's big, I gotta go now."
Continuity mistake: Near the start of the movie, Peter Parker is doing sit ups assisted by his friend. As the camera moves left, Peter is seen doing the exercise with both hands behind his head but as the camera then moves to a different angle he has both arms crossed over his chest with his hands at his shoulders.Nitram1967