Goalkeeper Bobby Olejnik left the Gulls for Peterborough this week, while Crawley have put in a bid for midfielder Eunan O'Kane.
Mansell, who is the club's longest-serving player, rates the pair highly but insists all is not lost.
"It's not the end of the world. Those two players did fantastically well for Torquay United and the people that come in to replace them may be as good or even better," Mansell told BBC Sport.
"Hopefully the gaffer can sign a few more and the board will give him some more money this time around and he can bring a few more fresh faces in."