Yes, if you do not have a separate ticket for the Oogie Boogie Bash, you must leave Disney California Adventure when the event officially begins. In 2026, the party typically starts at 6:00 PM, at which point the park is cleared of "day guests" to allow the private, ticketed event to commence. To facilitate this, Disney uses a "wristband" system. Throughout the afternoon, guests who have a valid Bash ticket can check in and receive a specialized wristband. Once the clock strikes 6:00 PM, Cast Members begin checking for these wristbands at every attraction entrance, restaurant, and shop. If you do not have a wristband, you will be politely but firmly directed toward the park exit. However, your day is not necessarily over; if you have a "Park Hopper" ticket, you can simply walk across the esplanade to Disneyland Park, which usually remains open for regular guests until 11:00 PM or midnight on party nights. This "sweeping" process is necessary to ensure the exclusive atmosphere and limited crowds that guests pay a premium for when attending these seasonal Halloween events.