Found using:

• Google VR SDK version: ___1.110.0
• Unity version: 2017.2.0f3
• Phone manufacturer, model, and O/S version: Windows 10

Steps to reproduce the issue:

1. Make an empty new scene
2. Switch to android
3. Set min API to 19
4. Enable VR support (Cardboard)
5. Add a reticle and a GVREditorEmulator
6. Enter play mode (alt + mouse does not work)

Workarounds:
Adding the GvrControllerMain solve this issue. But hey, I am building for cardboard, why do I need the GvrControllerMain?