Any of Your Business
When you first reach the cable car station, you'll spot a phone sticking out of a backpack. It's ringing, but go ahead and ignore it, zipping up the bag instead. This is really a tutorial on the Butterfly Effect, but not being nosy is just common courtesy.
Rats with Bushy Tails
When you assume control of Chris, you'll be able to blast a couple targets at the shooting range - including an innocent squirrel. Do not shoot the little guy.
The Soul of Discretion, Part 1
When you're first introduced to Ashley, she'll be spying on Emily and Mike through a telescope. Matt will enter after a moment, and you can choose whether to let him look through the telescope or not. Let him, and he'll see Emily flirting.
This isn't part of the Butterfly Effect menu, but it's important nonetheless. During Mike and Jessica's snowball fight, a bird will land on nearby table. Do not pelt him; let the timer run down instead.