The Predators have won four straight to improve to 5-1 in the preseason. The Capitals are 1-3-1.
Mathieu Perreault scored for Washington.
Perreault opened the scoring when he beat Pekka Rinne with a wrist shot at 6:41 of the first period. Wilson tied it in the period with a snap shot that Tomas Vokoun was unable to stop to his glove side.
Wilson has five points in four preseason games.
The Predators made it 2-1 midway through the second period on Halischuk's tip-in.
Weber skated low through the middle to beat Vokoun with 5:23 left in the second.
O'Reily closed the scoring early in the third.
|Mathieu Perreault (1) Wrist shot - ASST: Brooks Laich (1), Troy Brouwer (1)|
1 - 0 WSH
|Colin Wilson (1) Snap shot - ASST: David Legwand (1), Niclas Bergfors (1)|
1 - 1 Tie
|Matt Halischuk (1) Tip-in - ASST: Jordin Tootoo (1), Nick Spaling (1)|
2 - 1 NSH
|Shea Weber (1) Snap shot - ASST: Martin Erat (1), Craig Smith (1)|
3 - 1 NSH
|PPG - Cal O'Reilly (1) Snap shot - ASST: Shea Weber (1), Craig Smith (2)|
4 - 1 NSH
|Patric Hornqvist Holding the stick - 2 min against Sean Collins|
|Jordin Tootoo Cross checking - 2 min against Dmitry Orlov|
|Mike Knuble Hooking - 2 min against Mattias Ekholm|
|Mathieu Perreault Cross checking - 2 min against Colin Wilson|
|Cody Eakin Holding - 2 min against Mattias Ekholm|
|Karl Alzner Holding - 2 min against David Legwand|
|David Legwand Hi-sticking - 2 min against Mathieu Perreault|
|Troy Brouwer Hooking - 2 min against Shea Weber|
|Martin Erat Hooking - 2 min against Sean Collins|
|Mattias Ekholm Hi-sticking - 2 min against Jay Beagle|
|Nicklas Backstrom Slashing - 2 min against Niclas Bergfors|