When the Enterprise is pulled into the Borg Trans-Warp conduit, the effects shown while in the conduit are reused scenes from when the Enterprise was trying to escape from the energy vortex.
When Wesley and Geordi are in Data's quarters, one of them lifts up the covers to one of Data's paintings. The image on the painting is that of the top view of the energy vortex the Enterprise was caught inside of in Time Squared.