Thanks guys for the comments.

I just realized from your comments that some of my rivers are facing the wrong direction . And I think you are right about my mountains. Initially I used a mountain brush I created and scattered it around the map using size and scatter on the brush and deleted the mountains I did not required. Then I got my hands on some mountain brushes and started updating the landscape to add a pass and a volcano on the island and couple of other mountains which has resulted in the change in mountains. Wanted to keep the terrain stylized which is creating this problem so I'll probably revisit the landscapes.

Thanks once again for the advice.

Torg