There are no inconsistencies in the Gospels, they have been combed over, debated and vetted by millions of scholars by both those who have supported Christ and those who were not supporters of Christ over thousands of years.
There have been no inconsistencies discovered, what may be helpful to consider is that four people will see various aspects of a truth, the differences in any observations create a harmony that reveals the whole of a truth. In that regard John offers a view that is beyond the synoptic Gospels of Matthew, Mark and Luke and provides added context.