A credit report only contains information that relates to a person's credit history -- the history of his taking out loans and lines of credit. Other kinds of financial transactions that do not involve the extension of credit, such as the opening of a bank account or the the taking out an apartment lease, will not appear on a credit report unless the individual incurs a debt.
While the apartment lease itself will not show up on a person's credit report, if the landlord runs a credit check on the person before renting him the apartment, then this inquiry will appear on the credit report. However, a credit check for an apartment, while appearing on a person's credit report, will not affect the person's credit score, unlike some checks by creditors.
While an apartment lease would not show up on a credit report, an unpaid portion of the rent might show up if the tenant fails to pay the money he owes the landlord. Credit reports also contain records of bills that individuals have failed to pay on time. If a person is very late in paying the rent, then the landlord might report this debt to a credit reporting bureau.
The only way an apartment lease might show up on a credit report without it being delinquent would be if the lease were, contractually, set up as a loan. For example, a landlord could, at least theoretically, agree to rent a person an apartment for a full year, with the person paying at the end of the year. In such a case, the landlord might report this arrangement as a loan.