Principal photography is usually the most expensive phase of film production, generally due to actor, director, and set crew salaries, the costs of certain shots, including any props or on-set special effects. Its start generally marks a point of no return for the financiers, because until it is complete there is unlikely to be enough material filmed to release a final product needed to recoup costs. While it is common for a film to lose its greenlight status during pre-production – for example, because an important cast member drops out – it is extremely uncommon for finance to be withdrawn once principal photography has commenced.
Feature films usually have insurance in place by the time principal photography begins. The death of a star before completing all planned takes, or the loss of sets or footage can render a film impossible to complete as planned. For example, sets are notoriously flammable, and most older studios feature water towers for that reason.
Once a film concludes principal photography, it is said to have wrapped, and a wrap party may be organized to celebrate. During post-production, it may become clear that certain shots or sequences are missing or incomplete and are required to complete the film, or that a certain scene is not playing as expected, or even that a particular actor has failed to turn in a performance of the required caliber. In these circumstances, additional material may have to be shot. If the material has already been shot once, or is substantial, the process is referred to as a re-shoot, but if the material is new and relatively minor, it is often referred to as a pick-up.