When Jerry is talking to Kramer after his set, there's a large sweat mark on the front of his shirt; a moment later, when he's talking to Bania, the sweat mark is gone.
Elaine and Puddy take a taxi to the airport in Oslo Norway. When they arrive, the taxi driver says "Terminal 3". As of 2011, there is only one terminal at the Oslo airport.
On the flight back from Norway, the flight attendant is pushing a cart of sodas and snacks. Both Pepsi and Coke products are on it. Airlines always chose one or the other to get the lowest cost.
If Kramer had actually cooked his skin he would be in excruciating pain and be covered in 1st and 2nd degree burns.
Scooters go much faster than they appear to be on this show.
Rascals are a lot faster.
When Kramer starts spreading the butter on his face, his makeup colors the end of the stick.
When Puddy is looking through his coins in what is supposed to be Oslo, he says "femti kroner" which is 50 kroner. There is no coin of that value, only a bill.
If the container Kramer gets from the coffee shop is full of butter, it would be way too heavy for him to be carried in the way he does.
When Kramer goes to take a stick of butter from Jerry's fridge, a spray bottle of "I Can't Believe It's Not Butter" can be seen several times in pantry. There would not be a need for Jerry to have that product in his kitchen if he keeps fresh butter in his fridge.
A flight from Oslo to New York would take 10 hours maximum, even with a stop over in London.
Puddy and Elaine are supposedly in Oslo, yet when Puddy is counting his money, we can see out of the back of the car they are in. Not only does the road have a dual solid yellow line (in Oslo; it would be a single, dashed yellow line); but they pass by an American railroad crossing sign, the back of an American stop sign is visible, and they are obviously not in Europe at all.
Play Now would have an elevator.