During one of the final scenes where young Jed is saying goodbye to his grandfather Captain Joy lying in bed, Jed for a moment midway through his talk has a noticeable round lump near the right side of his mouth that wasn't there when he entered the cabin and wasn't there afterwards when hugging Mr Lunceford.
When their ship strikes an iceberg looming out of the fog bank Widmark grabs a rope and goes overboard to examine the damage. This is absurd when there are a dozen able-body sailors who could go below deck and safely report any hull damage. Furthermore the life expectancy in ice-laden sea water would be a matter of minutes - Widmark and a couple of other sailors are splashing around (getting crushed between the ship and the berg) like they're in a warm bathtub.
When asked what is the longest river in the world, Jed answers the Narragansett (not the Mississippi as noted elsewhere). This was a 19th century name for a complex of small rivers (now called the Blackstone, Seekonk, and Providence rivers) that empty into Narragansett Bay. The river system is located in Rhode Island and Massachusetts. Since Jed is from New Bedford, he would have been familiar with this river system and bay.
In the ship's log on OCCURRENCES and REMARKS for the captains Buried at sea this day entry it shows the date as Thurs,day. The 13. Of Jan. 1888. This date was actually on Friday.
Jed says that the longest river in the world is the Mississippi River. The Mississippi River is the second largest in the USA behind the Missouri River and would be considered the longest river in the USA. The Nile is the longest river in the world.