A cog invasion happens when the cogs take over a certain district. They were first released on March 20, 2003. They can happen at any time in any district. It is an army of one type of cog going to work.
- Main article: Cog summon
- On April 8, 2008, skelecogs invaded Toontown. Skelecogs cannot actually be summoned.
- Cog invasions allow cogs of the wrong level or type to be in a certain street. Case and point, the highest level cog that can normally be found in Toontown Central is level three. However, in a Mr. Hollywood invasion level eight cogs can be found there.
- When an invasion starts or ends, a message from the Toon HQ will pop up, making a "boing!" sound.
- Previously, the sound when a message from Toon HQ pops up is a "psst" sound.
- Mega cog invasions occur when there is an invasion of the same cog in every district except for safe zones.
- Invasions do not affect cog facilities.
- Skill points are doubled during an invasion.