The 2-1 loss leaves them eighth in the table with two games to play, with Bradford City now having a game in hand on Stags.
Stags host Harrogate Town at the weekend with Bradford heading to Northampton and Salford heading to Carlisle.
Match photographers Chris and Jeanette Holloway took these pictures of just some of the fans at the game.
Take a look and see who you know.
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1. Stags 1 Orient 2
Mansfield Town fans ahead of the defeat to Leyton Orient. Photo: Chris and Jeanette Holloway
2. Stags 1 Orient 2
Mansfield Town fans ahead of the defeat to Leyton Orient. Photo: Chris and Jeanette Holloway
3. Stags 1 Orient 2
Mansfield Town fans ahead of the defeat to Leyton Orient. Photo: Chris and Jeanette Holloway
4. Stags 1 Orient 2
Mansfield Town fans ahead of the defeat to Leyton Orient. Photo: Chris and Jeanette Holloway