In episode 5, level 5, the enemy you are watching at the start of the level will walk towards the wall, then perform a quantum leap backwards about 6 steps. Once alerted, he acts just like a normal enemy would.
Further detail: after teleporting backwards, he keeps walking towards the wall, and the second time he reaches it, he turns right and becomes alerted as expected. In the original Wolfenstein 3D, the first time he reaches the wall he turns right and becomes alerted.
From http://web.archive.org/web/20030119131317/http://hosting.gotdotnet.ru/DarkOne/phorum/showthread.asp?id=71 "Bug in v .7 and .72":
Further detail: after teleporting backwards, he keeps walking towards the wall, and the second time he reaches it, he turns right and becomes alerted as expected. In the original Wolfenstein 3D, the first time he reaches the wall he turns right and becomes alerted.