Salah, who has not been at his best since returning from injury last month, was brought on in the 79th minute, just after the Hammers' second goal levelled the game
Neymar strained his right adductor muscle and had to come off seven minutes into Brazil's 1-0 win over Cameroon on Tuesday, while fellow forward Mbappe fell awkwardly before halftime in France's 1-0 victory over Uruguay and was also withdrawn.
"They will undergo a 48-hour period of treatment before further evaluation," PSG said in a statement.
The French club are at home to Toulouse on Saturday and will hope to extend their record-breaking start to the Ligue 1 season with a 14th consecutive victory, before playing Liverpool on Nov. 28.
PSG sit third in Champions League Group C, a point behind leaders Napoli and Liverpool with two matches left to play.