Near the end of Planes, Trains, and Automobiles, when he's reached Chicago, Neal boards a train. Since his money was stolen and all of his credit cards had burned up, how did he pay?
This is addressed in the original script. Del paid for Neal's ticket with a little money that he had left over.
EXT. ELEVATED TRAIN PLATFORM
[Del and Neal lug the steamer trunk up the stairs. They set it down. Del reaches into his pocket and removes the last of the money.]
DEL: I'll pop for the token. Where you headed?
DEL: I'll be right back.
[Del shuffles over to the ticket window. Neal tries to straighten himself up. He brushes off his coat and pats his hair down.]
Considering that a great number of scenes ended up on the cutting floor, including scenes that would explain events that did make it to the end result (e.g. why did someone break into their hotel room and steal the money from Neal's wallet?), it is possible the explanation for this inconsistency was left out of the final movie.