Anything that can return light will cause it, the path is perfectly reciprocal unless you use an optical isolator (expensive, and lossy), but you can at least avoid the cube and other parts reflecting by setting stuff at slight angles.
Temporary use at low power during setup will help a LOT. Best keep it right down though, 10 mW, (30 max). That's safer for eyes too.
DPSS lasers are pretty much immune because the various coatings and crystals form a strong barrier to the output light getting back to do harm. It might be possible to destabilise the cavity enough to notice a flicker, but no more than that.