Factual error: The ferry splits in half down the middle...enough so the water is flooding in dramatically as the split grows. There is no possible way that the two halves of the ferry could have remained afloat like that. It would have sunk immediately. Then, as Iron Man "welds" the two halves back together, the ferry is afloat at the same waterline as before the incident...certainly not feasible with all the water it took on.
Continuity mistake: In Peter's personal vlog of the airport battle from Civil War, he jumps in, grabs Cap's shield and says 'Hey everyone'. However, in Civil War he jumps in and grabs the shield without saying anything, Tony says "nice shot kid", there's a longer chat about the suit, and only later does Spider-Man say "hey everyone".
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.
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.