Falling into a bathtub
The apartment was the first dream level in the heist on the mind of the Proclus Global head Saito. It was constructed by the architect Nash, who created the dream as a replica of a real hotel room that Saito kept and used to facilitate his various affairs.
Despite being called the "dilapidated hotel room" in the script for Inception, Saito referred to it as an apartment.
During the Saito extraction job, all the sleepers, excluding Nash, were already in the second dream level, while Saito's projections were raging outside and gradually closing in on them. Arthur was the first to wake, but as he was the dreamer of the Japanese castle, he knew that it was only a matter of time before the castle he had constructed would collapse. He then rushed to further sedate Saito before he woke, but he failed to do so in time.
Nash attempted to wake Cobb before Saito woke up by pushing him into a bathtub. Cobb woke and overpowered Saito, demanding the know the rest of the information that he had failed to extract in the level two of the dream. Saito tells the trio that he was unimpressed with them and had only let them enter his mind to test them for a future job.
Suddenly, a musical cue began to sound through the dream, warning Cobb that the dream was ending soon. Arthur was then woken up in reality. Cobb pushed Saito to the ground and demanded the information again, but Saito discovered that he was still dreaming when he felt that his carpet was not made of the proper material. Upon realizing this, his projections flooded the room, killing Cobb and Nash while Saito looked on bewildered.