Paul wrote that 500 people saw Jesus at once (1 Cor 15:6). If his recounting is true, it's obvious they saw something, but it's not clear to me why that thing couldn't have been a vague figure misinterpreted as Jesus. Here are some similar events:
108 people saw the Virgin Mary appear at a waterfall and then to the adults of the group at Mass. Link Among the observers were doctors, psychologists, psychiatrists, engineers, and lawyers.
A second example comes from Cairo, Egypt in 1986, at a Coptic church. Mary had appeared a number of times between 1983 and 1986. Once she appeared on the roof, four Coptic bishops arrived to authenticate the vision. They did indeed see her. At other times she was seen by (non-Christian, obviously) Muslims. Link
During the supposed Miracle of Fatima, many people claimed to see the sun exhibit strange behavior, whirling toward the earth. Link
Betty Parris (age 9) and her cousin Abigail Williams (age 11), the daughter and the niece, respectively, of Reverend Samuel Parris, began to have fits described as "beyond the power of epileptic fits or natural disease to effect" by John Hale, the minister of the nearby town of Beverly. Link
Sixty-two pupils at the Ariel School aged between six and twelve said that they saw one or more silver craft descend from the sky and land on a field near their school. Some of the children claimed that one or more creatures dressed all in black then approached and telepathically communicated to them a message with an environmental theme, frightening them and causing them to cry. Several of them have maintained their account into adulthood. Link