Liverpool forward Mane, who played the full 90 minutes of his country's friendly match in Paris, opened the scoring midway through the second half by coolly converting from the spot.
Senegal were pegged back almost immediately, though, as Fulham loanee Gohi Cyriac equalised.
Gomez, meanwhile, completed 90 minutes in England U21s' 4-0 victory over Denmark in Randers.
Earlier on Monday, Alexander-Arnold came off the bench as England U19s made it three wins from three European Championship qualifiers with a 5-1 defeat of Belarus.