GDC-0449 and Erlotinib Hydrochloride With or Without Gemcitabine Hydrochloride in Treating Patients With Metastatic Pancreatic Cancer or Solid Tumors That Cannot Be Removed by Surgery

Inclusion Criteria: * Histologic proof of a solid tumor that is now unresectable, not amenable to any other standard therapies, or patient refuses standard therapy * Metastatic adenocarcinoma of the pancreas amenable to biopsies (cohort II MTD only) * Absolute neutrophil count (ANC) \>= 1,500/μL * Platelets \>= 100,000/μL * Total bilirubin =\< upper limit of normal (ULN) * Aspartate aminotransferase (AST) =\< 3 times upper limit of normal (ULN) * Creatinine =\< 1.5 times ULN * Hemoglobin \>= 9.0 g/dL * International Normalized Ratio (INR) within normal limits (for patients treated at the MTD) * Ability to provide informed consent * Willingness to return to Mayo Clinic for follow up * Life expectancy \>= 12 weeks * Willingness to provide the biologic specimens as required by the protocol * Negative serum pregnancy test done =\< 7 days prior to registration * Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-2 * Able to swallow or have medication administered through a G-tube and absorb the medication * Participant agrees to use an acceptable form of contraception; acceptable forms of contraception: * Latex condom (always used with spermicide) * Diaphragm (always used with spermicide) * Cervical cap (always used with spermicide) Acceptable forms of secondary contraceptions, when used along with a barrier method: * Hormonal contraception methods, including pills, patches, rings, or injections except progestin-only containing pills (i.e. "Mini-pill"…