You are referring to the following verse “After that he appeared in another form unto two of them, as they walked, and went into the country” (Mark 16:12).
But a couple of verses after Mark 16:12, and in specifically 14, we see that Jesus appeared to His disciples and they all recognized Him “Afterward he appeared unto the eleven as they sat at meat, and upbraided them with their unbelief and hardness of heart, because they believed not them which had seen him after he was risen.”
The reason why the two men did not recognize Jesus, in Mark 16:12 and Luke 24:16, was because He shut their eyes to give them a chance to believe in Him based on what the scriptures say and not on their visual senses “But their eyes were holden that they should not know him.” At the end of that story, they recognized Him when Jesus broke the bread “And their eyes were opened, and they knew him; and he vanished out of their sight” (Luke 24:31).
We can be sure that everyone will recognize Jesus when He returns in glory “And then shall they see the Son of man coming in a cloud with power and great glory” (Luke 21:27). And even the evil people will recognize Him so much that they will mourn “And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory” (Matthew 24:30). He will come back just as the disciples saw Him go, and He will be recognized by all.
When Jesus comes back, it will be the loudest, most lighted up event that this world will ever experience.
In His service,