Striker Kashket scored one goal in 22 appearances for the O's and has joined on a contract until 31 December.
Gape, 21, was captain of Southampton's Under-21 side last season and has made one Premier League appearance.
The pair join amid an injury crisis that has left more than a third of the Chairboys squad in the treatment room.
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Wycombe have signed Scott Kashket after his Leyton Orient contract was terminated and Southampton midfielder Dominic Gape on loan until 3 January.