Looking at the Spongebob Squarepants Battle for Bikini Bottom Rehydrated graphics compared to the Original. In order to get the secret ending you must collect all Patrick’s socks & obtain all of the golden spatulas in each level.
Spongebob Squarepants Battle for Bikini Bottom Rehydrated vs Original Ending Cutscenes:
0:45 Original Secret Ending
1:30 Remake Secret Ending