Young striker Moses had to be substituted towards the end of Tuesday night's goalless draw with Sheffield Wednesday after sustaining an ankle knock.
Defender McCarthy played despite a virus and boss Neil Warnock expects him to get worse before he gets better which could rule him out.
Fellow centre-half Davis was sidelined by the same virus in midweek but he could have recovered in time for Saturday and will be in line for his second Palace debut if McCarthy misses out.
Strikers Freddie Sears (ankle) and Stern John (elbow) are still out, although both should be close to returning after the international break.
Meanwhile, Blackpool boss Ian Holloway will again be without a number of players.
Defenders Ian Evatt (hamstring) and Danny Coid (tibia), midfielder Ishmel Demontagnac (hamstring) and strikers Daniel Nardiello (hip), Gary Taylor-Fletcher (ankle ligaments) and Stephen McPhee (knee) all look set to remain sidelined.
Demontagnac has returned to light training but is unlikely to feature at Selhurst Park as the Seasiders aim to bounce back from Tuesday's 2-0 defeat at Bristol City.
It was only Blackpool's second loss of the season and shunted them out of the Coca-Cola Championship play-off places.
Holloway is demanding an immediate reaction from his players and said: "I believe they will respond to what I've said."