When Carl and Frank are talking, they say that their Dad died ten years ago, but in the episode "We're Going To Disney World", Mother Winslow says that their father died before Disney World was even built, which was in 1971.
Carl obviously doesn't want to talk to his brother in any way, but in episode 1 he suggests to call Frank to get his mom to stay with him. I guess because it was nine years earlier, and they only hadn't talked to each other for one year at that time, Carl wasn't as angry as he was nine years later.
Frank: (at the front door in his clown costume) Hi!
Harriette: Can I help you?
Frank: First you can give me a great big hug! (approaches Harriette)
Harriette: (in a karate stance) You better stay back, jack!
Steve: Not so fast, Buttercup! You have one more challenger!
Steve: You're looking at 'im!
Butterball: No, I'm laughing at 'im!
The German episode title is "Die Herausforderer", meaning "The Challenger".