Easter Eggs
Below is a listing of various easter eggs within the game.
Compass-chan Surprise
When you get a ship drop, extend the window and click on the upper left third of the black area (the cursor will change to a hand) to get the COMPASS-CHAN CLASSICAL DANCE PARTY.
Non-functional repair cancellation dialog
The "cancel repair" dialog is a function that is likely removed from the game. After placing ships in the repair dock, stretch the game window horizontally until there's a significant amount of wide black space on the left and right sides. Clicking on the space on the left will display the dialog, which does not actually cancel anything if "yes" is selected. Note that selecting "yes" also causes various bugs to occur.
Bug bouncing in the visual gallery
The fairy (with the books on her head) in the gallery also has a bug on top. If you click on the fairy, the bug will bounce, and sometimes fly away. There has been a mini-game where some people see how many times they can click on the bug before it flies off (record on the Japanese Wiki seems to be 78 times).