This is the whole map with all the Easter Eggs highlighted (except those specific to an event). It is up to date as of July 2020.
Older version from June 2018 can be found here
Clicking on any of the easter eggs when visible will give you a reward (multiple click required for the sheeps). If you own Junkman, you have a chance to get an extra reward on top of the normal reward.
|Fox||Rank1 Ingredient||2x Rank1 Ingredient|
|Fruit of World Tree||1000||1x|
|Gumball||300|| 1x Rank1 Airship Materials
1x Rank2 Airship Materials
|Sheep||Plant Extract||2x Magic Bean Pod|