In the movie "Wizard of Oz", why did the winkie guards creep up behind and attack the Scarecrow, Tin Man, and Lion? How did they win?

[Oliverlogan263]

In the scene where Scarecrow, Tin Man, and Lion plan to get Dorothy out of the witch’s castle, How did the guards even knew they were there to come behind them and attack them?

[strateguy632]

the gate gards didn't see but from castle tower or flying monkey saw and sent.

[clampfan101]

I imagine how they were found was by following Toto.
How they won was with plot armor. lol

[Paris13]

Working For The Wicked Witch, I Think. xxoo

[FunkyMonkee]

Toto told them they were there.