"Could be the past; could be another world. That's the thing about hijacking a portal, it's a crapshoot." - Terror Mask
Portals are magical forms of transportation. According to the Terror Mask, portals open up in places where the barriers between reality are weaker. During the course of Splatterhouse (2010), Rick Taylor uses portals transport himself to different locations while trying to rescue Jennifer. Unfortunatley for him, Portals seem to appear randomly and could take him to unknown locations. Dr. West claims that he has mastered portal travel, and knows where each portal leads to. The Terror Mask is capable of creating portals if enough blood has been spilled. In their 2010 appearance, portals appear to be purple ghost-like mouths with tentacles surrounding them.
One portal appears as a gate to the "void" in Splatterhouse 2, as mentioned by West's diary. It is revealed that the real Jennifer is inside, so Rick breaks the seal at the cost of monsters leaking for her sake. While Jennifer is safe at the end, this sets into motion the events of Splatterhouse 3.