The calendar page sail on the boat with which Rudolph sails through the Archipelago of Last Years is labeled as "August 1928," but the calendar page is November 1928.
Father Time mispronounced the "arch" in "archipelago" several times as "ARCH", before switching over to the correct pronunciation "ARK" later on in the story.
Father Time says that Happy leaves the 1 Million BC island on a conch shell. It was actually a scallop shell.
When Rudolph reaches the Sands of Time, he worries about how to cross them until Quarter-Past-Five arrives. Rudolph was a flying reindeer, so he could have flown there much more quickly than the lumbering camel could have taken him.
After Father Time tells Rudolph why Happy ran away when they all laughed at his big ears, he also explained that they didn't mean to be cruel while laughing. Yet Rudolph still assumes that they also called him names and wouldn't let him join in New Year games. This doesn't make sense, because Father Time's statement contradicts Rudolph's.