Contradiction with Matthew 14:20
John 6:13 mentions twelve baskets of fragments gathered, while Matthew 14:20 speaks of the same event but does not specify the quantity of baskets in that particular gathering, though both accounts indicate a gathering of fragments.
Matthew 14:20: And they did all eat, and were filled: and they took up of the fragments that remained twelve baskets full.
Contradiction with Luke 9:17
While Luke 9:17 aligns with the miracle of feeding the multitude, it does not specify what happens to the leftover fragments like John 6:13 does, creating a different emphasis.
Luke 9:17: And they did eat, and were all filled: and there was taken up of fragments that remained to them twelve baskets.
Contradiction with Mark 6:43
John 6:13 specifies the baskets contained barley loaves, while Mark 6:43 mentions twelve baskets but does not specify the type of loaves, although both recount the same event.
Mark 6:43: And they took up twelve baskets full of the fragments, and of the fishes.