Striker Vaughan joined the Eagles on three-month loan deal from Everton on Wednesday and could partner Pablo Counago in attack at the Madejski Stadium.
Defender Gardner arrived on transfer deadline day from Hull and could also find himself thrust straight into the starting line-up with Palace having lost their last three Championship matches.
Young forward Wilfried Zaha serves the second game of his three-match ban.
Skipper Paddy McCarthy was forced off during the first half of the defeat at Scunthorpe last time out through illness but has recovered.
Midfielder Darren Ambrose is still out with a leg injury and joins David Wright (calf), Sean Scannell and Lee Hills (both knee) on the sidelines.
