When Johnny is in the food kitchen line, a homeless lady behind him yells at him for holding up the line. When Johnny finally gets his food and turns around, the same homeless lady is sitting at a nearby table with food already.
When Kreese finishes his meeting with Johnny at the bar, he drinks and empties his glass of whiskey; in the next scene the glass still has the whiskey in it.
When Daniel exits the taxi in front of Tomi Village Green, he stares at the mall that's there, then starts walking towards the mall, neglecting to get his luggage from the cab. Later, while Daniel is shown looking at all the shops, he has his luggage again.
The US servicemen who briefly appear in Daniel's Okinawa trip are not wearing any patches or nametapes on their uniforms, and are wearing incorrectly colored t-shirts.
In the bar scene, Kreese orders a Cutty and water. Cutty is a Scotch whiskey and is nowhere as dark of a liquid as what appears in his glass.
While having tea with Kumiko, Daniel says that he's the same age now that Mister Miyagi was when he met him. While Ralph Macchio is roughly the same age now that Pat Morita was when the first film was made, the character Daniel turned 16 at the end of 1984, making him 51 when the episode takes place, while Miyagi states in the second film that his father taught him how to fish in 1927, which would've made him 62 or 63 at the youngest in the first film.
At 20:47 Daniel says "I am the same age now that Mr. Miyagi was when he met me." However, the headstone in season one reveals that Miyagi was born in 1925, making him 59 in 1984 when the pair met. Daniel was 16 at that time, so being as the episode takes place in 2018, Daniel is actually 50.