Anachronisms: Alex puts the contents of a pack of Jacobs coffee into GDR packaging, but the logo on the Western coffee package is the one that was launched in the late '90s.
Anachronisms: A bottle of red Blanchet brand wine is shown, but when the wall came down, there was only Blanchet white wine.
Anachronisms: A GT6N-type streetcar, which was not in service before 1995, can be seen in the summer of 1990.
Anachronisms: In one sequence in the background you can see the Berolina-Bulidung at the Alexanderplatz. On the roof you can see the sign of the bank company "Bankgesellschaft Berlin". In the time between the fall of Berlin-wall (Nov.1989) and Germany's reunion (October 1990) there was no Bankgesellschaft Berlin situated in East-Berlin. The Company bought the Berolina Building in 1993.
Anachronisms: When Alex first enters the hospital to pay a visit to his mother, there are modern green emergency exit signs.
Incorrectly regarded as goofs: Denis wears a Matrix-style t-shirt in 1989 because he has developed the "letter idea" himself and has come up with an idea for a film exactly like The Matrix (1999), which he describes in a deleted scene (the letters are not identical to the Matrix scheme.) The joke is that the idea originated in East Germany; compare the claim in one of Denis's fake news shows that the Coca-Cola formula was invented there.
Anachronisms: When Alex goes to the supermarket to buy his mom's favorite pickles, he asks an employee where to find them. The employee is tagging cases of Pepsi. The Pepsi logo on the cans is the modern day logo, not the one in the early-'90s.
Continuity: After Ariane finds the letters from her father hidden in the kitchen, she holds one on which Christiane's name is misspelled as Christine.
Revealing mistakes: As Alex is being driven away from his mother in the truck at night, you can see faint blue sky in the background.
Anachronisms: When Christiane goes out from her GDR home into the real world, an ad for IKEA is visible. The label is in yellow and blue, and wasn't launched until 1999. The earlier logo was white and orange/red.
Continuity: In the scene where Alex convinces Dr. Klapprath to come to his mother's birthday, the amount of coffee in the pot on the table changes between shots.