Detailed Explanation

 Okemo Mt. Down and Out!, implicates the following laws:
 

1. As noted in Issue 84, one may not directly or indirectly cause his/her fellow a financial loss.

2. One is liable for direct damages, both intentional and unintentional. One is liable and should pay as well, for intentional indirect damages. One is absolved from paying for unintentional indirect damages.

3. The Heavenly Court retains the sole right to prosecute an offender to pay for indirect damages. Beis Din is vested with the power to prosecute for direct damages [Choshen Mishpat 386].

4. Nevertheless, by assuming responsibility to safeguard 1) movable property 2) currency 3) fiat money or 2) livestock, [see Issue 72 for process] - (all of which bear inherent or attributed value and can be physically moved from the depositor's domain to the trustee's domain) a trustee becomes liable and can be held accountable in Beis Din for damages or losses due to his/her negligence etc. albeit an indirect cause of the loss or damage [Exodus 21: 6-14].

5. A borrower is liable for loss or damages even beyond his/her control [Choshen Mishpat 340].

6. [As noted in Issues 72 and 83, assuming responsibility to safeguard "people" implicates zero liability within the trustee framework. Unless otherwise specifically legally stipulated from the onset (or common practice dictates otherwise), a guardian over a child/adult is absolved from damages due to negligence etc.]

7. Similarly, the Torah excludes safeguarding instruments of debt (whose value simply indicates the existence of a debt/financial responsibility) and stationary property or real estate (which cannot be physically moved from the depositor's domain to the trustee's domain) from the trustee framework. Unless otherwise specifically legally stipulated from the onset (or common practice dictates otherwise), a guardian over instruments of debt or real estate is absolved from damages due to negligence etc.

Application

Wonder Passes

Aaron and Emmy borrowed the Whitman's Wonder Passes. Aaron lost the Wonder Passes. Superficially, as a borrower, Aaron is liable to reimburse the lender should the pass go lost. 

However, employing a more critical look, the Wonder Passes are neither movable property, legal currency, fiat money, or livestock. Instead, they are instruments of debt, which oblige the attraction sites to deliver services to the pass bearers upon displaying the passes. Presumably, the Whitman's did not  perform a legally binding stipulation to hold  Aaron liable for trustee liabilities. Thus, while Aaron should have been more careful with the Whitman's passes, the Whitman's would not be able to require Aaron to reimburse them with new passes.

Burst Pipe

Aaron and Emmy borrowed the Whitman's vacation home. Emmy's turning off the running water resulted in the pipes freezing overnight. The extensive damage was an indirect result of Emmy's action.

There are two angles through which we can absolve Emmy from paying for the ensuing damages.  As a city girl, she was clearly unaware that shutting off the water could have put the pipes at risk of bursting. Unintentionally and inadvertently causing indirect damage, she would be absolved from paying for the damages.

Nevertheless, as a borrower, Emmy theoretically should be liable even for accidental damages. Nonetheless, as the vacation home is a piece of real estate, Emmy does not assume trustee liabilities without having entered a legally binding stipulation at the onset of the arrangement.

Generally,  home renters sign contracts which legally binds them to various damages to the property during the rental term. However, it is uncommon for people who lend out their home to have the borrowers sign a contract legally binding them for damages thereof. Hence, we can reasonably assume that the Whitman's did not have Aaron and Emmy sign such a contract. As they simply lend the vacation home to Aaron and Emmy, they are absolved from paying for accidental damages that occur during their stay. [Of course, they would be liable for direct damages they cause to the property].

 Answered by: The Fellow - Yesharim Research Center