When Kimmy first enters the kitchen, baby Tommy isn't in the shot but when the camera goes to the rest of the family and then back to Kimmy, he's suddenly in his high chair like he had been there the whole time. No one would have been around to put him in there.
When DJ is in the kitchen and talking about how all of the chores will now be her responsibility, the camera goes back and forth to DJ and each time, the boxes on the calendar change names.
When DJ is talking to her dad about selling the house, in different shots, her right hand is in different places. It's either grasping the side of the water bottle, holding her purse, or holding the bottom of her water bottle.
Jesse and the Rippers attend the going away party and play the song "Forever" despite an 8th season story arch where Jesse was fired from The Rippers and he strove to surpass their success with his new band. However, it's not unreasonable to believe that, at some point over the course of 20 years, they could have made peace and reunited (especially if their 2013 performance on "Late Night With Jimmy Fallon" is considered canon).
It would be impossible for Joey to continue doing ten shows a week in Las Vegas if he has to commute between there and San Francisco like he says he would. The drive time would be at least eight and a half hours without traffic or stopping for breaks.
When Max is listing the "bad words," when he gets to Donald Trump, it clearly looks like he is saying something completely different.
When little Max says (about Kimmy's feet being on the table), "Yeah but they smell like Trump," his mouth is actually saying, "crap". The line seems to have been re-dubbed to more fitting humor of the times. The original line was probably an inside joke to words the original show could not use back then ... especially by the kids.
Jesse and the Rippers attend the going away party and play the song "Forever" despite a story arc in the final season where Jesse was fired from The Rippers and he strove to surpass their success with his new band. However, it's not unreasonable to believe that, at some point over the course of 20 years, they could have made peace.