Phil's current will grants Will a considerable amount of inheritance, which is equal to, or worth more than, Carlton's portion.Which is why Carlton always mentions that he hasn't revised his will whenever there is the slightest chance of Phil dying when resolving an episode's conflict.
The entire series is Will's coma-dream.The opening credits decribe Will getting "in one little fight" (against several, larger guys) in the rough neighborhood he grew up in. This results in a coma, wherein he dreams about a life far removed from the urban hell of West Philadelphia in the 90's.
Carlton and Nicky formed an in-universe version of LMFAO.''The Fresh Prince of Bel-Air was based on Benny Medina's experiences with the Gordy family. LMFAO consists of Stefan Gordy and his nephew Skyler. Replace "nephew" with "younger brother" and you can almost imagine Will promoting them. Just look at some of the dorky dancing in their videos; it's all Carlton.
The entire series takes place in Heaven, because Will is dead.(Note: this theory was originally from this BuzzFeed article) Will actually died in the fight on the basketball court in West Philly. The taxi driver is actually God, who drives a "rare" cab. He takes Will to heaven, where he works out all his issues with his wealthy Aunt and Uncle. Will only sees his mother and father on special occasions, because that's when they come to visit his grave.
There wasn't any Job OfferAt the end of Papa's Got A Brand New Excuse, Will's Father claims he has been offered a job that would put him on the road for lengths of time and would have to cancel the cross country trip Will had been hoping for. The problem is, there wasn't any. He was just making it up so he wouldn't have to tell Will he was leaving again. Considering he never said what he was doing or who he was going to be working for. He made that up as an excuse cause he refuses to accept responsibility for what happened to Will due to him walking out when he was a kid and cause him to be a slightly troubled teenager growing up.
Philip actually is Will's Father.Considering they have the same skin tone and Will doesn't look anything like his real Dad I wouldn't be surprised if Phil and Will's mother had a one night stand before he was introduced to Vivian that left her pregnant and he never knew and she didn't tell anybody.